IN  our  last  issue  we  gave  an  account  of  the  greatest  silver-lead  mine  in 
the  world,  the  Broken  Hill  Proprietary  of  the  Barrier  Range,  New  South 
Wales.  It  is  now  announced  that  a  new  silver-lead  discovery  in  the  same 
district  perhaps  equals  in  extent  this  great  mine.  The  following  particulars 
of  a  mine  in  Queensland,  Australia,  the  Mount  Morgan,  the  greatest  gold 
mine  in  the  world,  will  also  be  of  interest.  The  balance  sheet  for  the 
half  year  just  ended  shows  that  the  receipts  for  the  six  months  were 
$3,738,675,  including  about  $75,000  carried  forward  from  the  previous 
half-year's  operations.  Out  of  this  $2,875,000  have  been  distributed  in 
dividends  and  about  the  same  amount  has  been  carried  forward  as  was 
brought  into  the  account.  The  dividends  declared  for  the  first  nine  months 
of  the  present  year  amount  on  an  average  to  $500,000  a  month,  or 
$4,500,000.  The  average  production  of  gold  is  over  1,000  ounces  per  day, 
and  it  is  stated  that'  the  amount  oi  ore  iii  sight  would  warrant  even  a 
larger  plant  than  is  in  use.  The  ore  is  refractory  and  lias  given  consid-; 
erable  trouble  in  attaining  a  satisfactory  extraction,  but  as  its  average 
value  is  over  four  ounces  to  the  ton,  there  is  a  good  margin  to  work  on. 
The  orejs  treated  by  chlorination  in  barrels,  usingthe 


plant,  to  which  process  the  ore  is  admirably  "suited.  One  impression  that 
we  gather  from  these  accounts  as  from  those  of  the  Broken  Hill  mine  is 
that  the  properties  are  not  only  ably  but  honestly  administered  and  in  this 
respect  are  an  example  to  rnanyjindertakings  in  other  countries. 


Mount  Morgan  Mine  and  Newberry-Vautin  Process. 
EDITOR  ENGINEERING  AND  MINING  JOURNAL: 

SIR:  An  article  appeared  in  your  issue  of  October  12th.  page  811,  in 
which  you  gave  some  particulars  of  the  Mount  Morgan  Mine,  Queensland, 
which,  as  far  as  the  figures  go,  I  quite  indorse,  but  the  concluding  part, 
in  which  you  state  that  "  the  ore  is  treated  by  el  dor  i  nation  in  barrel*,  us- 
ing the  Newberry-Vautin  plant,  to  which  process  the  ore  is  admirably 
suited.'' 

This  statement  is  incorrect.  The  Newberry-Vautin  plant  originally 
erected  has  been  abandoned  for  some  years.  The  process  now  in  use  is 
the  Mears  chlorination  process,  using  chlorine  gas  under  pressure  (of 
chlorine)  in  a  revolving  vessel  or  barrel  (an  American  invention). 

The  alleged  improvement  of  Newberry-Vautin  was  air  or  steam  pressure 
applied  to  the  ore  mass  after  the  pressure  of  chlorine  had  been  ob- 
tained, for  which  they  got  a  patent.  The  latter  invention  was  certainly 
new.  Where  air  pressure  ha*  been  used  it  has  been  abandoned. 

Yours  truly,  CHI. OH  INK. 

SYDNEY,  Australia.  November  27th.  1X83.  • 


THE  ENGINEE 


8[C 

air 
ai< 


Aq 
si' 


mittal.  Here  we  have  two  kinds  of  metallic  iron,  quick.silve: 
sulphate,  and  in  the  ore  sulphides,  antimonides,  arsenides,  1 
dides,  metallic  silver,  and  as  bases  copper,  lead,  zinc,  iron,  c? 
all  of  the  alkalies  and  alkaline  earths — so  that  there  are  an  in 
sible  reactions  which  can  be  imagined.  If  one  works  out  the 
the  Berthelot  plan  of  thermo-chemic  reactions,  that  the 
the  one  which  develops  or  absorbs  the  greatest  number  of  1 
will  have  the  choice  of  some  two  hundred  series  of  equatio 
that  was  the  number  reached  by  one  experimenter  in  inve 
true  inwardness  of  the  matter,  the  final  outcome  being  as  pro 
before  the  calculations  were  begun. 

Mr.  Eissler  has  made  a  good  point  in  f rowning  upon  the  ii 
use  of  ' '  chemicals  "  in  amalgamation.  Every  mill  man  kn< 
sage-brush  extract,  tobacco  juice,  etc.,  are  not  efficaceous 
Mr.  Eissler  himself  advocates  the  use  of  free  sulphuric  acid  ; 
to  oxidize  chalcopyrite  to  bluestone.  If  some  of  our  mill  n 
five  or  ten  stamps,  two  or  four  pans,  one  or  two  settlers  anc 
to  work  on  amalgamation  without  chemicals,  repeating  on  th 
the  experiments  of  Mr.  Arnold  Hague,  they  would  probably 
supposed  "medicines"  could  be  suppressed  without  being  mi^ 
a  few  ounces,  or  even  up  to  four  pounds,  of  bluestone  in  •< 
charge  seems  ridiculous.  If  the  experiment  is  tried  in  a  glase 
salt  and  a  little  scrap  iron  on  the  bottom,  it  will  be  foun< 
copper  is  at  once  precipitated  in  the  metallic  state  on  the 
reduced  to  subchloride  from  dichloride,  as  the  most  commc 
theory  requires.  And  after  chloridizing,  roasting  with  tht 
per  cent,  or  more  in  the  furnaces,  it  seems  absurd  to  add  sail 
pans,  as  Mr.  Eissler  did  at  Mineral  Hill.  There  is  almost  alw 
of  salt,  and  such  excess  is  detrimental  in  two  ways:  by  co 
mercury  as  calomel,  and  by  leaching  out  the  silver  chloride 
slimes. 

Still,  with  its  defects,  Mr.  Eissler'**  book  is  a  good  one. 
good  deal  of  hitherto  unpublished  records,  and  bears  on  e 
mark  of  the  experienced  metallurgist,  not  a  mere  maker  of  b 


CORKESPONDENCE, 


We  invite  correspondence  upon  matters  of  interest  to  the  industries 
metallurgy.  Communications  should  invariably  be  accompanied  witl 
address  of  the  writer.  Initials  only  will  be  published  when  so  request 

All  letters  should  be  addressed  to  the  MANAGING  EDITOR. 

We  do  not  hold  ourselves  responsible  for  the  opinions  expressed  by  < 


£rt 


Value  of  the  Machinery  and  Supply  Column, 
EDITOR  ENGINEERING  AND  MINING  JOURNAL  : 

SIR:    '•  I  find  your  innovation  of  apprising  you 

Machinery  Wanted  of  great  value.     Yours  truly, 

ElCHARD  j. 
MARQUETTE,  Mich.,  Sept.  20th,  1889.  Minim 

Gypsum, 
EDITOR  ENGINEERING  AND  MINING  JOURNAL  : 

SIR  :  As  a  subscriber  to  your  paper,  I  have  been  unable  to 
ticle  treating  of  gypsum  mining  in  the  United  States. 

I  find  gypsum  in  your  annual  list  of  mineral  products,  but  J 
able  to  find  out  in  which  States  it  is  mined.  Having  lately 
large  bed  of  this  mineral  in  Arkansas,  I  would  be  very  thai 
for  information  as  to  which  States  it  is  mined  in,  as  I  intern 
if  competition  does  not  stand  in  the  way.  I  of  course  know 
Eastern  markets  only  Nova  Scotia  gypsum  is  used. 

[Gypsum  is  a  hydrated  sulphate  of  lime,  its  chemical  com} 
expressed  by  the  formula,  CaSO42H2O.  It  occurs  in  vark 
formations,  especially  in  tertiary  deposits.  In  its  transpare 
state  it  is  known  as  selenite;  when  it  presents  a  finely  fibre 
appearance  it  is  termed  satin  spar,  and  the  pure,  milky  \v 
varieties  are  called  alabaster. 

Production. — In  this  country  the  principal  sources  of 
Ohio    and    Michigan.     The    production    of    the    latter    (• 
was  54,810  short  tons.     The  average  price  of  land  plaster  \v 
and  of  calcined  plaster  $10  per  ton  or  $1.50  per  barrel  of  300 
the  total  product,  28,794  tons  were  for  use  as  land  plaster  a? 


OA\;  jo 

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SUTAVO^OJ  aq;  SAVoqs  ^SS-B  aqj, 
m  ao:o  p^a{  aq^  a^i^un 
uo;sauiT|  aq;  ui  '^UT^[  '^q'eq; 
§nB^j^  'uvfprg  ^  apoj  -B  raojj  ajo 
:o  sajdni'Bs  araos  pamra-Bxa 
pui3 


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aq  X'BUI  ;Bq;  Xu-Bdraoo  Xa-Bipisqns  ^U-B  jo 
saj'Bqs  aq;  jo  q;ua;-auo  PUB  'aonpojd  aq; 
uodn  ^;^Xoj  ';uao  jad  g  jo  ;uara^d  -B  jo 
aq;  uodn  ^jo;ijaa;  S;T  jo  apqAV  aq; 
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5joo;s  aq;  UT  ssauisnq  os 


qou'Bjq  -B  jo 

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I'Bas   s^uudraoQ   aq^   ysi\%   HA\ou5[ 
^i  uaqAv  pasn'BO  S-BA\. 
jo  pap  pooS  y     *asu 

op   'pa^aodaa  J'BJ  os 
^nq  i  dn  paqsnj  aq   |^TAV  saa^qs  pui? 

-B  aq  ^qnopou  tji 
saqo-Baa  SAvau  aq^  naq^\ 
pa^Avdn  n'B  aA-Bq  ^|ps  pu'B  'an^A  nt 
paAOjdini  Ap'Baap  aA-Bq  saj'Bqs  ,/JrBJ,,  «ois 
-saadxa  aq^  jo  A'ji'Bioadsa  pu-B  {siq^  jo 
aqc^  uj  'Jiiij  aaaA\.  ^oadsojd  aq^ 
paB  ^SBg;  aq^  pn^  -Btpj^sny  paspdans 
qoiqAv.  auo^s  qoia  ^jnjjapnoAv  aq-;  auiB» 
j  qn'B^;  „  snoni'Bj  aq^  jo 
^o§  uaaq  S'Bq  aa^-BAv  aq^ 
autua  qnis^j  aq^  jo  aa^BtrBin 


r  '   - 

NOTES 

ON      THE      TREATMENT 


OF 


GOLD     ORES. 


BY 


FLOKENCE     O'DRISCOLL, 

*i 

ASSOC.  M.  INST.  C.E. 


OFFICES     OF     "ENGINEERING,"    LONDON; 

AND 

JOHN    WILEY    &    SONS,    NEW    YORK. 
1889. 


CONTENTS. 


INTRODUCTION      .... 

CHAPTER  I. 

SOME  OF  THE  PROPERTIES  OP  GOLD 

CHAPTER  II. 
OCCURRENCES      

CHAPTER  III. 

REMARKS  ON  THE  PROCEDURE  OP  LATE  YEARS 


LOSSES 


FREE  MILLING    . 


PARAGRAPHS 


CHAPTER  IV. 


CHAPTER  V. 


REMEDIES  . 

CHAPTER  VI. 


CHAPTER  VII. 


3 


,       12 


21 


29 


66 


167 


189 


390306 


NOTES  ON  THE  TREATMENT 


OF 


GOLD  ORES. 


INTRODUCTION. 

IN  the  following  pages  an  endeavour  is  made  to  place- 
before  the  public  certain  particulars  on  the  subject  of  Gold 
Ores  and  their  treatment,  in  such  a  form,  that  a  reader 
who  has  no  knowledge  of  the  subject  may  be  able,  after 
perusal,  to  have  some  fairly  clear  idea  of  the  outlines 
of  the  matter  written  upon.  It  is  desired  to  avoid 
technicalities  and  scientific  phraseology,  so  wherever, 
for  sake  of  brevity,  use  is  made  of  any  such  words  or 
^erms,  in  the  majority  of  cases,  where  first  used,  an 
explanation  by  foot-note  is  appended. 

No  pretension  is  herein  made  of  having  treated  the 
subject  exhaustively ;  only  the  essential  details  are 
touched  upon  ;  nor  is  any  attempt  made  to  theorise  on 
the  formation  of  veins,  or  the  deposition  of  gold 
in  them.  It  has  been  a  very  difficult  matter  to  keep  the 
notes  within  the  limits  originally  laid  down  ;  in  some 
cases  this  has  been  exceeded,  but  when  so,  it  is  hoped 

B 


4  .  Properties. 

microscopically  it  will  be  found  to  consist  of 
minute  particles  of  crystalline  gold  ;  but,  if  a 
globule  of  metallic  gold  be  subject  to  the  same 
flame,  the  operator  may  continue  blowing  for  an 
indefinite  period,  and  no  sublimation  or  altera- 
tion in  the  size  of  the  globule  will  result. 

MALLEABILITY. — One  grain  of  gold  may  be  beaten  into 
leaf  until  it  covers  a  superficial  area  of  56  in.,  and 
is  of  a  thickness  equalling  ^To^th  °f  an  incn- 

DUCTILITY. — One  grain  of  gold  may  be  drawn  into  a 
wire  of  500  ft.  long  ;  a  grain  of  gold  in  a  globular 
form  is  about  equal  in  size  to  a  No.  9  shot,  and 
measures  .073015  in.  in  diameter 

SOLUBILITY  (see  pages  5-11). 

CRYSTALLOGRAPHY. — The  cubical  system ;  the  most 
common  forms  being  octahedrons^  and  dodeca- 
hedrons, t 

NATURAL  ALLOYS. — Native  gold  is  almost  always  found 
alloyed  with  a  proportion  of  silver  ;  this  varies 
so  greatly  in  different  localities,  that  no  general 
statement  can  be  made  to  indicate  the  proportion  ; 
but  the  higher  the  proportion  the  more  closely 
do  the  forms  approach  those  of  native  silver. 
Rhodium,  palladium,  mercury,  copper,  iron,  and 
bismuth  are  amongst  the  other  metals  with  which 
gold  is  found  naturally  alloyed;  in  some  deposits 
it  occurs  with  tellurium,  and  bismuth  in  what 
appears  to  be  a  definite  chemical  combination. 

VALUE. — The  value  of  pure  gold  at  the  London  Mint  is 
4Z.  4s.  ll^d.  per  ounce  troy;  roughly  stated  at 
4s.  3d.  per  pennyweight  and  2d.  per  grain. J 

|   Particulars  regarding  value  are  added   so  as  to  make 
the  information  on  the  subject  more  complete. 


/       A  Natural  SulpMde  of  Gold. 

The  existence  of  gold  in  the  form  of  a  natural 
sulphide,  in  conjunction  with  pyrites,  has  often 
been  advanced,  theoretically,  as  a  possible  oc- 
currence, but  up  to  the  present  time  this  occur- 
rence has,  I  believe,  never  been  established  as 
an  actual  fact.  During  my  investigations  on 
the  ore  of  the  Deep  Creek  mines,  New  South 
Wales,  I  have  found  in  them  what  I  believe  to 
be  gold  existing  as  a  natural  sulphide.  The 
description  of  this  ore  will,  no  doubt,  be  of  in- 
terest to  your  readers. 

The  lode  is  a  large,  irregular  one  of  pure 
arsenical  pyrites,  existing  in  a  felslte  dyke  near 
the  sea  coast.  Surrounding  it  on  all  sides  are 
micaceous  schists,  and  in  the  neighborhood  is  a 
large  hill  of  granite  about  800  feet  high.  In 
the  lode  and  the  rock  immediately  adjoining 
it  are  large  quantities  of  pyrophyllite,  and  in 
some  parts  ot  the  mine  are  deposits  of  this  pure 
white  translucent  mineral,  but  in  the  ore  itself 


it  is  a  yellow  and  pale  olive  green  color,  and 
never  absent  from  the  pyrites. 


is 


Properties. 


n 


HYDROCHLORIC  ACIDS  (aqua-regia), 
VND  NITRIC  ACIDS, 
NITROUS  ACIDS, 


t 

YANIDES, 

f  other  chemical  substances  under 
ns  which,  though  very  interesting, 
oiselves  of  sufficient  practical  im- 

From  the  very  first  I  was  much   struck   with  .      . 

the  exceedingly  fine  state  of   division  in   which  llSCUSSed  in  this  inquiry, 
the  gold  existed  in  the  ore.      After  roasting .       ,  ,  .      ,          , 

and  very  carefully  grinding  down  in  an  agate  luble  Salts  DV  the  elements ! 
mortar,  I  have  never  been  able  to  get  any 
pieces  of  gold  exceeding  one-thousandth  of  an 
Inch  in  diameter,  and  the  greater  quantity  is 
very  much  finer  than  this.  Careful  dissolving 
of  the  pyrites  and  gangne  so  as  to  leave  the 
gold  intact  failed  to  show  particles  of  any  larger 

S±"£  £  iS^Sr^^SKof  the  same   in  certain  reactions. 
£±?  WS2£3S££3£«I2£  are  distributed  throughout  nature 
X-b«»iphide.n°thll"!  'eftbnt  t0  tMt  '"lowing  manner  : 
•^TW&Bft^Vafert  commonly  in  combination  with 

It  finely  and  heating  for  some  hour,  with  a  aloride  of  Sodium    Or  Common    Salt. 
solution  of  sodium  sulphide  (Na«  83),  on  decom- 
posing the  filtrate  and  treating"  it  for  gold,  is  fa  one  of  the   most   widely   dis- 

By  far  the  largest  sources 
it   is   also    found    very 
the 


—  -  —  is 

*ot  a  result  at  the  rate  of   12  ounces  gold  per  '"' 

ton.    This  was  repeated  several  times  with  the  tture 

»me  result.     This  sample  came  from  the  lode 

»t  the  140-foot  level,   while   samples   from   the  ock     Salt 

ligher  levels,  where  the  ore  is  more  oxidized, 

although  carrying  the  gold  in  the  same   degree  tore    Or  leSS  in  most    Waters,   in 

af  fineness,  do  not  give  as  high  a  percentage  of 

mrio  sulphide.  riiinal  bodies,  and  to  a  lesser  extent 

It  would  appear  that  all  the  gold  in  the 
pyrites  (and  I  have  never  found  any  apart  from 
It),  has  originally  taken  its  place  there  as  a  sul- 
phide. The  following  is  an  analysis  of  a  general 
sample  of  the  ore  :  Silica,  13.940%;  alumina, 
3.592%;  lime,  0.9025%;  sulphur,  16.584%; 
irsemc,33.267%;iron,  27.720%;  cobalt,  0.964%; 
nickel,  traces;  gold,  5  ozs.  3  dwts.  8  grs.  per 
ton;  silver,  16  dwts.  per  ton;  total,  99.969%.— 
T.  W.  T.  Atherton,  in  Eng.  and  Mining  Jour. 


om. 

E. — Though  not  in  such  large 
they  are  very  widely  distributed 
;  and  manner,  especially  in  marine 
:  of  sodium  and  iodide  of  sodium, 
.ons,  not  otherwise  in  animal  or 


f  Gay-Lussac. 


6  Properties. 

Before  any  compounds  of  the  foregoing  are  in  a  state 
to  act  as.  solvents  for  gold,  decomposition  must  take  place 
to  set  "free"  the  active  element,  and  in  the  constituents  of 
the  earth's  crust  the  chemicals  to  produce  these  reactions 
are  found  widely  distributed.  As  an  illustration  of  how 
nature  may  work,  the  following  is  cited  :  The  manufac- 
turer in  order  to  produce  chlorine  mixes  sulphuric  acid, 
manganese  (manganic  oxide),  and  common  salt ;  sul- 
phuric acid  combines  with  the  sodium  and  hydrochloric 
acid  is  produced  ;  manganese  supplies  oxygen  to  take 
the  hydrogen  from  hydrochloric  acid,  thus  finally  "  free- 
ing" or  liberating  the  chlorine  ;  the  chemical  equations 
for  the  reactions  are  as  follows  : 

NaCl      +        H2S04  HC1          +        Na  H  S04 

Common  salt  +  Sulphuric  acid  =  Hydrochloric  +  Sodium  hydrogen 

acid  sulphate* 

4  H  Cl     +        Mn  O2  C12  +  2  H2O  +  Mn  01, 

Hydrochloric  +      Manganic      =     Chlorine      +  Water  +  Manga- 
acid  oxide  nous  Chloride 

In  nature  these  reactions  may  take  place  as  in  the 
workshop  of  the  manufacturer.  Sulphuric  acid  is  not 
only  a  natural  product  of  volcanoes,  but  it  is  formed  in 
very  large  quantities  by  the  decomposition  of  pyrites  or 
mundicf  deposits.  Common  salt  is  to  be  found  in  the 
waters  percolating  the  soil  of  the  earth's  crust.  It  is 
easy  to  conceive  that  sulphuric  acid  and  common  salt  are 
continually  coming  into  contact  and  liberating  hydro- 
chloric acid  ;  this  coming  into  contact  with  manganese, 
or  other  substance  with  similar  properties,  finally  sets 
chlorine  free. 

As    already   noted,    wherever   masses    of   pyrites    are 

*  Such  salts  are  sometimes  called  acid  sulphates. 

f  A  miner's  term,  which  includes  all  common  mixtures  of  sulphides 
and  arsenides  found  in  mines. 


Properties.  7 

decomposing,  the  quantity  of  sulphuric  acid  found  is  very 
great.  A  large  number  of  other  minerals  are  present,, 
which  with  sulphuric  acid  at  once  brings  about  a  chemical 
change ;  thus  giving  rise  to  the  mineral  sulphates  found 
in  veins  and  deposits.  After  these  reactions  are  satisfied, 
any  surplus  of  sulphuric  acid  is  left  free  to  act  upon  the 
common  salt  contained  in  the  water  percolating  the  de- 
posits, and  hydrochloric  acid  is  formed,  which,  in  turn, 
coining  into  contact  with  an  oxidising  agent,  evolves  free 
chlorine. 

Pyrites  almost  invariably  contains  gold  in  relatively 
minute  particles  ;  the  decomposition  of  pyrites,  with  sub- 
sequent liberation  of  chlorine  in  close  proximity  to  this 
gold,  causes  the  immediate  formation  of  a  gold  chloride 
(Au  C13)  soluble  in  water. 

The  reactions  bringing  about  the  liberation  of  free 
bromine  and  iodine,  and  the  formation  of  soluble  gold  salts, 
take  place  from  similar  causes  and  in  the  same  manner  as 
explained  in  the  case  of  chlorine. 

Before  closing  the  subject  of  solubility,  it  may  aid  the 
general  understanding  of  the  case  to  describe  briefly  how 
these  solvent  agencies  affect  such  other  metals  as  are 
generally  associated  with  pyrites.  Although  chemical 
geology  is  extremely  interesting,  it  is  almost  an  inter- 
minable subject,  therefore  a  number  of  intermediate  reac- 
tions which  must  take  place,  but  do  not  interfere  with 
the  main  issue,  are  purposely  omitted.  Dealing  witk 
the  only  important  metals  affected  by  the  breaking  down 
or  decomposition  of  pyrites  deposits  :  Any  carbonates  of 
lime,  magnesia,  baryta,  &c.,  are  at  once  converted  into 
sulphates  by  the  action  of  sulphuric  acid ;  iron  is  con- 
verted into  oxide,  sulphate,  and  carbonate  ;  lead  into  sul- 
phate and  carbonate ;  arsenic  enters  into  combination 


8  Properties. 

with  iron,  lime,  &c.  ;  copper  becomes  a  sulphate  or  car- 
bonate ;  sulphide  of  silver  decomposing  under  the  condi- 
tions enumerated,  and  in  the  presence  of  salt  water, 
forms  chloride  of  silver.  All  these  reactions,  in  all 
probability,  occur  before  the  liberation  of  free  chlorine, 
bromine,  or  iodine  takes  place. 

In  cases  where  all  the  sulphuric  acid  evolved  is  con- 
sumed in  bringing  about  the  first-mentioned  reactions, 
there  is  nothing  left  to  form  solvents  for  gold,  there- 
fore the  metal  remains  as  it  was  and  where  it  was  prior 
to  the  decomposition  of  the  pyrites,  and  the  miner  will 
find  it  in  the  gossan  of  the  deposit. 

That  the  foregoing  reactions  take  place  in  nature  the 
following  tends  to  prove :  On  certain  goldfields  where  the 
rocks  are  covered  with  little  or  no  surface  soil,  it  may  be 
noticed  that  long  lines  of  brown  iron  ore  (hydrous  oxide 
of  iron)  cross  the  field  in  the  direction  of  the  strike  of 
the  lodes,  sometimes  running  along  the  outcrops,  in  other 
cases  following  fissures  or  cracks  on  the  true  strike  of  the 
rocks  containing  the  lodes  ;  this  oxide  of  iron,  in  many 
instances,  may  be  traced  to  quartz  veins,  and  is  a  pro- 
duct of  decomposing  pyrites. 

Careful  examination  of  the  lodes  reveals  the  following  : 
On  and  near  the  surface  oxide  of  iron  is  found  in  hard 
compact  masses,  sometimes  botryoidal  or  stalactitic  ;  this 
as  far  as  it  extends  is  called  the  cap  of  the  lode.  Below 
the  cap,  the  quartz  lode  proper  is  met,  and  on  examina- 
tion it  will  be  found  that  the  joints  and  surfaces  are 
stained  and  coated  with  compact  oxide  of  iron,  which 
also  fills  some  of  the  cavities  in  the  stone.  Deeepr  down 
the  lode,  the  vascular  rock,  highly  charged  with  oxide  of 
iron  and  known  as  gossan,  is  found  in  the  joints  and 
cavities,  in  a  spongy  and  friable  form ;  it  is  the  mineral 


Properties.  9 

matter  left  after  the  decomposition  of  the  pyrites,  and  the 
removal  in  solution  of  soluble  substances.  Below  this, 
at  the  water  level  of  the  lode,  the  brown  iron  ore  is 
entirely  lost  in  the  soluble  iron  salts  and  decomposing 
pyrites.  And  immediately  beneath,  again,  the  solid 
.and  unaltered  pyrites  is  found  ;  in  highly  mineralised 
lodes  this  zone  of  decomposition  is  very  clearly  marked 
by  a  line  of  black  friable  decomposing  mundic  with  iron 
in  the  form  of  soluble  sulphates  immediately  overlying 
the  still  unaltered  mineral  matter.  The  gold  in  this 
mineral  matter  in  the  decomposing  zone  and  in  the 
gossan  is  found  in  irregular  and,  more  or  less,  crystal- 
line particles  ;  the  sizes  of  the  particles  found  under 
similar  circumstances  vary  greatly  in  different  lodes. 
Sometimes  the  gossan  is  very  rich  in  gold,  sometimes  it 
appears  as  if  some  of  the  gold  had  been  dissolved 
out,  sometimes  it  is  blank,  which  naturally  leads  to  the 
supposition  that  whatever  gold  it  contained  had,  at 
some  previous  time,  been  carried  off  in  solution  by  water; 
nearer  the  surface  there  is  strongly  confirmative  evidence 
for  this  supposition.  As  the  lode  is  traced  upwards,  the 
gossan  is  found — if  gold-bearing — to  bear  gold  and  be  of 
the  nature  described,  until  the  cap  is  met.  The  more  or 
less  hard  compact  oxide  of  iron  forming  the  cap  of  the 
lode  is  found  to  be  impregnated  with  gold,  in  entirely 
different  forms  to  that  below.  The  joints  of  the  stone 
are  frequently  found  covered  with  a  gold  film,  so  that  any 
one  not  versed  in  the  subject  might  often  mistake  it  for 
a  purple  iridescence  left  by  an  iron-impregnated  water  ; 
again,  the  shape  and  size  of  the  deposited  films  are  such 
as  to  preclude  all  possibility  of  their  having  found  their 
way,  through  the  natural  filter-bed  of  the  lode,  from  the 
gold-bearing  pyrites  below,  unless  carried  in  solution  by 


10  Properties. 

water  and  there  precipitated.  The  impregnation  of  the 
hard  compact  masses  of  the  cap  by  microscopically  fine 
gold,  is  accounted  for  by  the  water  carrying  a  solution  of 
both  iron  and  gold,  and  on  evaporation  under  atmo- 
spheric action,  the  gold-impregnated  solidified  iron  oxide 
is  found. 

A  peculiarity  of  such  formation  is,  that  the  caps  of 
these  lodes  are  much  wider,  more  confused  and  indefinite 
than  the  lodes  beneath  ;  this  is  accounted  for  by  the 
corrosive  action  of  the  mineral  waters  destroying  the 
original  confining  walls  of  the  lodes  and  eating  back 
into  the  country  rock.  In  the  distribution  of  gold 
through  this  cap  there  is  another  peculiarity  observable. 
Although  the  lode  underneath  may  be  (say)  2  ft.  or  3  ft. 
wide,  the  cap  may  be  20  ft.,  40  ft.,  100  ft.  wide  or  more; 
and  yet  not,  so  to  speak,  proportionately  dilute  in  gold, 
as  compared  with  the  narrow  body  of  lode  from  which  it 
derived  its  origin.  It  is  generally  as  rich  as  the  lode 
beneath,  in  many  cases  far  richer  in  patches,  yet  there 
are  in  this  great  mass  many  blank  patches  also.  The 
formation  of  gold-bearing  patches  of  greater  or  less  rich- 
ness is  accounted  for  by  the  belief  that  from  great  lengths 
of  the  lode,  the  drainage  waters,  bearing  gold  in  solution, 
find  their  way  to  the  surface  in  comparatively  constricted 
outlets  and  precipitate  the  metal  from  its  solutions, 
throughout  the  masses  of  rock  in  these  outlets  which  had 
already  been  corroded  and  altered  by  solvent  agencies 
before  mentioned. 

Although  in  nature  the  solvent  solutions  for  gold  may 
be  indefinitely  dilute,  the  geological  ages  are  indefinitely 
long,  during  which  the  result  of  accumulating  action 
brings  about  tangible  results,  and  though  chlorine  is  of 
this  class,  the  most  widely-spread  element,  bromine,  and 


Properties,  1 1 

iodine,  in  lesser  quantities  are  continually  acting  in  a 
similar  manner. 

Nitro-hydrochloric  acid  (aqua-regia)  is  the  ordinary 
solvent  for  gold  in  most  manufactures,  but,  owing  to  cost, 
it  is  not  as  yet  of  value  to  the  gold  producer  as  a  collecting 
medium,  Other  solutions  not  compounds  of  the  active 
elements  dealt  with,  are  all  distributed  throughout  nature 
and  are  continually  carrying  on  their  solvent  actions,  but  in 
a  degree  of  such  lesser  magnitude  as  to  be  outside  the  limits 
of  the  present  inquiry  ;  should  any  reader  be  desirous  of 
investigating  the  matter  further  much  information  will 
be  found  in  the  writings  of  BischofF,  Sterry  Hunt,  and 
others. 

It  may  be  well  to  reiterate  that  the  description  of  these 
reactions  is  in  no  way  an  attempt  to  theorise  upon  the 
origin  of  auriferous  deposits. 


12  Occurrences. 


CHAPTEE  II. 

OCCURRENCES. 

GOLD  exists  in  nature  under  widely  different  condi- 
tions, which,  for  the  present  purpose,  may  be  classed 
under  two  heads  : 

ALLUVIAL  DEPOSITS. 
DEPOSITS  IN  THE  MATRIX. 

ALLUVIAL  DEPOSITS. — The  greatest  gold  accumulations 
known  are  those  which  have  been  discovered  in  the 
gravels  or  earthy  deposits  of  long  disused  river  beds  and 
streams,  and  in  places  which,  from  their  extent  and  other 
indications,  appear  to  have  been  the  beds  of  seas  or  lakes. 

The  sizes  and  forms  in  which  the  metal  is  found  are 
very  variable.  It  is  found  as  "  dust,  "  "  nuggets, " 
thin  plates,  flakes,  crystals,  &c.  Miners  apply  the  word 
"  nugget "  in  a  very  general  sense  ;  any  piece  of  gold 
weighing  above  two  or  three  pennyweights  being  termed 
a  "  nugget,"  while  the  same  name  is  given  to  all  large 
masses  found.  The  individual  weight  of  many  have 
exceeded  1500  oz.  troy,  and  in  some  instances  over 
2000  oz.  in  weight  has  been  reached  by  single  pieces. 
"  Dust"  covers  the  infinite  variety  of  sizes  from  particles 
so  finely  divided  as  to  be  held  in  suspension  by  water  for 
considerable  periods  of  time,  up  to  the  size  known  as 
"  nuggets."  There  is,  however,  a  variation  in  name 
sometimes  used,  such  as  "  shotty  gold "  for  granular 


Occurrences.  13 

pieces  like  the  smaller  sizes  of  shot.  Often  a  rudimentary 
form  of  crystal  may  be  traced  in  some  derivative  from 
the  cube  ;  but  though  pieces  are  generally  water-worn, 
many  perfect  crystals  have  been  found.  It  may  be 
assumed  that  crystalline  forms  are  much  more  common 
amongst  the  finer  sizes,  than  in  large  pieces;  micro- 
scopic examination  frequently  reveals  this  to  be  the 
case. 

The  precise  depths  from  the  surface  at  which  the  metal 
is  found,  varies,  by  reason  of  denudation  and  other  causes, 
in  an  almost  indefinite  manner.  In  a  general  sense  the 
richer  deposits  are  obtained  in  the  last  few  inches  of 
material  covering  the  bedrock,  but  some  of  the  most 
remarkable  finds  yet  made  have  been  on  or  within  a  few 
inches  from  the  surface.  In  the  beds  of  rivers  and  gorges 
gold  deposits  have  been  found  in  successive  layers  or 
bottoms,  one  above  the  other,  and  when  so  occurring, 
though  generally  divided  by  alluvium,  cases  have  been 
known  where  conglomerate  rocks,  and  even  beds  of  basalt 
or  other  igneous  rocks,  have  intervened  between  the 
deposits  of  gold  ;  such  occurrences  have  given  rise  to 
great  argument  amongst  miners  as  to  the  difference 
between  true  and  false  bottoms.  When  deep  sinkings 
are  made  to  reach  alluvial  deposits,  they  are  known  as 
"  deep  leads."  Sometimes  when  these  are  put  down  or 
tunnels  driven,  it  is  found  that  the  physical  features  of 
the  country  have  been  entirely  altered,  and  that  the 
ancient  river  bed,  having  in  it  a  stratum  of  gold,  has 
been  covered  by  accumulations  so  as  to  become  a  hill  or 
watershed,  consequently  the  modern  river  finds  quite 
another  channel,  frequently  far  removed. 

The  positions  in  which  large  nuggets  are  found  vary 
in  the  most  extraordinary  manner.  Some  have  been 


14  Occurrences. 

picked  up  amongst  the  grass  roots,  others  in  the  roots  of 
uprooted  trees,  many  have  been  found  surrounded  by  soft 
soil  far  above  the  bedrock ;  in  fact,  frequently,  the  first 
indication  a  miner  has  of  one  is  either  striking:  it  with 

o 

his  pick  or  seeing  it  shining  amongst  the  mass  of  sur- 
rounding earth  or  debris.  The  story  may  be  cited  of  the 
finding  of  the  "Welcome  Stranger,"  the  largest  nugget 
yet  discovered.  Near  Dunnolly,  Victoria,  two  miners, 
weary  and  broken  down  by  toil  and  disappointment,  were 
aimlessly  wandering  about,  having  failed  to  obtain  further 
supplies  from  the  storekeeper  who  had  hitherto  given  them 
credit.  They  felt  that  they  had  come  to  the  end  of  their 
tether,  and  "  a  smoke  "  was  the  only  solace  left  for  their 
woes.  One  of  the  men  preparatory  to  lighting  his  pipe, 
stuck  his  pick  into  the  ground.  It  struck  something 
hard  and  dull  sounding,  which  caused  them  to  investi- 
gate, the  result  being  in  a  few  minutes  the  laying  bare  of 
a  mass  of  gold  weighing  2195  oz.  troy,  bearing  the  mark 
of  the  pick. 

Gold  is  also  found  as  "  dust "  in  the  sea  sands  on  the 
coast  of  California,  New  Zealand,  and  other  places,  and 
in  the  detritus  of  many  rivers.  Some  of  these  deposits 
have  been  of  great  value,  but  many  present  little 
or  no  permanence ;  for  that  which  one  day  is  visible  and 
workable  may  the  next  be  covered  deep  with  sand  or 
carried  by  currents  to  other  localities. 

Alluvial  gold  has  generally  a  smaller  proportion  of 
silver  and  other  metals  alloyed  with  it  than  gold  obtained 
in  rocks  and  veins.  The  minds  of  chemical  geologists 
are  still  exercised  in  endeavouring  to  account  for  this 
peculiarity. 

DEPOSITS  IN  THE  MATRIX. — The  occurrence  of  gold  in 
rocks  and  veins  presents  even  greater  peculiarities  and 


Occurrences.  1 5 

varieties  of  form  than  those  of  the  alluvial  deposits 
just  dealt  with.  The  following  are  some  of  the  forms  in 
which  it  is  found:  Crystals,  specks,  flakes,  spangles, 
filaments,  branches,  wires,  threads,  leaf-like  and  sponge- 
like  forms,  irregularly  shaped  lumps  of  all  sizes,  from 
dust-like  particles  to  that  which  in  alluvial  gold  would 
be  considered  large  nugget  sizes  ;  and  there  is  known  to 
exist  even  a  finer  division  than  that  which  may  be  termed 
dust ;  for  in  certain  cases,  where  microscopic  examination 
showed  no  gold,  considerable  quantities  have  been  obtained 
by  chemical  treatment. 

It  is  now  beyond  doubt  or  argument  that  by  far  the 
greater  wealth  of  gold  ore  deposits  at  present  known  are 
those  wherein  the  metal  exists  in  finely  divided  particles 
disseminated  throughout  vein  structures  and  deposits. 
In  like  manner  a  very  general  occurrence  of  gold  is 
in  association  with  the  sulphides  and  arsenides  of  iron, 
and  the  sulphides  of  copper,  lead,  zinc,  antimony,  and 
bismuth.  The  miner  as  a  rule  classes  any  mixture  of 
the  above  under  the  general  term  mundic  or  pyrites. 
Although  by  some  it  is  considered  a  debatable  question 
as  to  whether  gold  is  chemically  combined  or  mecha- 
nically held  in  these  compounds,  the  balance  of  evidence 
is  strongly  in  favour  of  the  latter  condition,  and  to  this 
view  most  of  the  leading  metallurgists  of  the  day  are 
inclined.  When  so  occurring  it  is  indisputable  that  in 
the  majority  of  cases  gold  is  in  a  state  of  extreme 
division,  so  much  so,  that  to  describe  it  as  fiour  would  be 
a  poor  illustration  of  its  finely  divided  condition.  There 
are  certain  large  auriferous  districts  where  the  metal  is 
found  almost  entirely  associated  with  the  above-mentioned 
compounds,  but  these  districts  are  not  the  sole  localities 
wherein  it  is  so  deposited ;  in  gold-producing  districts 


16  Occurrences. 

where  the  veins  carry  free  gold,  patches  of  gold-bearing 
sulphides  are  frequently  met  with  ;  and  in  many  localities 
free  gold  and  gold-bearing  sulphides  are  very  evenly 
mixed  throughout  the  deposits. 

The  popular  and  eagerly  sought  auriferous  deposits  are 
those  in  which  gold  is  here  and  there  visible  in  irregularly 
shaped  particles,  though  such  an  occurrence  by  no  means 
denotes  richer  deposits  than  those  carrying  invisible  gold 
or  gold-bearing  compounds  ;  indeed,  it  is  frequently  found 
that  the  latter  are  more  dependable  in  their  return  of 
metal.  There  are  numberless  instances  of  the  occurrence 
in  veins  of  heavy  gold-bearing  patches  of  stone  of  great 
value,  where  the  metal  was  in  large  and  irregularly 
shaped  particles,  sometimes  in  flakes  and  plates,  like  ham 
in  a  pile  of  sandwiches.  One  of  the  most  valuable  of  these 
discoveries  was  in  the  Hill  End  Mine,  near  Sydney,  New 
South  Wales.  The  patch  of  stone  in  question  was  about 
5  ft.  high,  and  on  an  average  1  ft.  wide  and  6  in.  thick, 
it  was  full  of  gold  in  the  form  of  threads,  wires,  lumps, 
and  irregularly  shaped  particles,  and  its  value  was,  in 
round  figures,  15,000/. 

Another  form  in  which  gold  occurs  is  that  in  the 
world-famous  Mount  Morgan  Mine,  near  Rockhampton, 
Queensland.  The  deposit  presents  several  interesting 
features,  as  may  be  seen  from  the  following  brief 
description,  which  embodies  the  observations  of  Mr. 
Jack,  the  Queensland  Government  geologist. 

The  mountain,  situated  about  thirty  miles  from 
the  sea,  is  surrounded  by  a  tableland,  above  which 
it  rises  about  400  ft. ;  the  summit  being  1225  ft.,  and  the 
average  altitude  of  the  table-land  about  800  ft.  above  sea 
level.  The  country  rock  consists  of  a  sandstone  forma- 
tion, with  occasional  masses  of  hard  shale,  and  in  the 


Occurrences.  17 

immediate  locality  of  the  mountain  it  is  intersected  in 
every  direction  with  intrusive  masses  of  igneous  rocks, 
such  as  rhyolite  and  dolerite.  At  the  time  of  Mr. 
Jack's  report  the  geological  evidence  seemed  to  prove 
to  him  that  the  mountain  has  resulted  from  the 
upward  flow  of  a  thermal  spring  carrying  silicious, 
-argillaceous,  and  other  matter,  in  a  semi-liquid,  mud-like 
mass.  The  summit  of  the  mountain,  when  opened 
out,  was  found  to  be  a  mass  of  silicious  brown  hematite 
ironstone  with  a  stalactite  structure,  together  with  what 
appeared  to  be  a  cellular  silicious  sinter  ;  this  had  a 
frothy  appearance,  and  was  sometimes  light  like  pumice- 
stone.  In  one  part  of  the  first  cutting  on  the  summit 
was  found  a  band  of  kaolin  in  various  states  of  purity. 
Throughout  the  whole  mass  gold,  exceptionally  free  from 
alloy,  occurred  in  the  most  minute  powder,  rarely  visible 
to  the  unaided  eye,  to  the  amount  of  from  5  oz.  to 
8  oz.  to  the  ton  of  deposit;  it  assays  99.7  fine;  the 
alloy  is  copper  with  minute  traces  of  iron,  and  it 
is  worth  4/.  4s.  8d.  per  ounce  troy.  Quarries  lower 
down  the  mountain  revealed  even  more  complexity  in 
the  deposited  mass  :  Brown  hematite,  red  hematite, 
aluminous  iron  ochre,  white  silicious  deposits,  soft 
aluminite,  masses  of  magnesian  and  aluminous  silicates, 
and  loose  silicious  sinter,  in  almost  all  of  which  gold 
occurs  similarly  and  to  much  the  same  amount  as 
previously  mentioned.  The  hillsides  formed  by  the 
overflow  are  of  like  character,  and  carry  gold  in  the  same 
manner  as  the  interior  of  the  hill ;  but  no  gold  has  yet 
been  obtained  in  the  locality  which  cannot  be  traced  to  the 
influence  of  the  deposit  and  the  surface  indications, 
resulting  from  its  gradual  denudation.  When  Mr.  Jack 
examined  this  mountain  for  the  purpose  of  reporting  on 
it  to  the  Queensland  Government,  very  little  work  had 


18  Occurrences. 

been  done  there.  The  opinions  he  then  expressed  are 
probably  those  that  any  other  skilled  geologist  would 
form  with  the  same  data  to  judge  from.  As  this  great 
deposit  is  now  well  opened  out,  and  much  is  to  be  seen 
which  could  not  have  been  guessed  at  when  Mr.  Jack 
was  there,  a  different  explanation  is  now  feasible  to  that 
of  the  "  thermal "  theory  then  propounded.  Recent 
investigations  would  justify  the  classing  of  the  occurrence 
as  a  remarkable  and  unusual  development  of  the  set  of 
causes  set  forth  on  pp.  8-10  as  an  explanation  of  the 
deposits  found  above  decomposing  pyritous  lodes.  It 
seems  that  this  Mount  Morgan  is  the  result  of  aqueous 
action,  by  which  the  deposited  portions  of  a  large 
mundic  lode  beneath  have  been  carried  upwards  and 
accumulated  on  the  surface.  That  which  appears  to  be 
silicious  sinter  of  geyser  origin  is  the  silicious  skeleton 
from  which  granular  iron  pyrites  have  been  dissolved  out 
by  natural  causes.  Specimens  exist  where  one  part  of 
a  stone  is  apparently  solid  pyrites  and  the  other  half 
sinter.  In  several  instances  pieces  of  the  solid  parts 
have  been  treated  with  nitric  acid  and  the  pyrites  dis- 
solved out,  then  a  framework  of  iron-stained  silica  was 
left,  not  to  be  distinguished  from  the  silicious  sinter  of 
thermal  origin.  Investigations  have  revealed  the  exist- 
ence of  a  large  pyrites  lode  underlying  the  deposit,  but 
this  is  not  yet  worked  for  gold.  Within  the  last 
five  years  gold  to  the  value  of  several  millions  sterling 
has  been  extracted  from  the  ore  taken  out  of  the 
workings,  and  as  far  as  can  be  judged  from  these 
investigations,  the  mountain  throughout  is  a  mass  of 
heavily  charged  gold-bearing  deposit ;  its  value  is  still 
undeterminable  because  of  the  difficulty  experienced  in 
obtaining  a  data  as  to  depth  and  extent. 

The  gold  carried  in  rocks  and  veins   is  sometimes  in 


Occurrences.  1& 

a  crystalline  form,  but  in  the  majority  of  instances  this 
is  not  very  clearly  defined,  though  with  the  smaller 
particles  the  edges  of  the  crystals  are  more  apparent ;. 
often  that  which  appears  to  the  unaided  eye  to  be  a 
thread  or  film  of  gold  is,  upon  microscopic  examination,, 
discovered  to  be  an  aggregation  of  more  or  less 
dislocated  minute  crystals — one  built  upon  the  other. 
In  fact  the  more  closely  the  occurrence  of  gold  is 
examined  the  stronger  is  the  evidence  of  its  deposition 
from  solution  in  separate  and  minute  particles. 

Another  form  in  which  gold  occurs,  far  more  wide- 
spread, and  of  incalculably  greater  aggregate  value,  than 
any  other  yet  known,  is  :  the  gold  carried  in  the 
waters  of  the  ocean — this  is  not  just  now  available 
for  general  circulation.  >  That  gold  is  present  in  all  sea 
water,  and  may  be  determined  easily,  is  not  a  matter 
of  dispute  ;  it  is  held  in  solution,  presumably  in  the  form 
of  bromides  and  iodides  ;  Sonstadt  estimated  that  it  is 
present  to  the  extent  of  nearly  one  grain  to  the  ton  of 
water,  or,  roughly,  to  the  value  of  two  pence. 

The  early  alchemists  seem  to  have  stumbled  across 
some  traces  of  this  fact  in  their  search  after  the  secret  of 
transmutation.  As  might  be  expected,  their  notions  on 
the  subject  were  extremely  visionary  and  indistinct,  and 
were  first  given  to  the  world  in  1350  by  the  monk 
Odomar,  who  stated  that  the  salt  of  the  sea  was  the 
mercury  of  the  philosophers  or  chief  ingredient  to  be  made 
use  of  in  the  composition  of  the  wonderful  stone  which  was 
to  turn  all  that  it  touched  into  gold.^  He  found  many  fol- 
lowers, among  them  the  famous  Bernard  of  Trdves,  who, 
thinking  (as  he  said)  that  "the  ocean  was  the  mother  of 
gold,"  set  up  in  1432  a  laboratory  on  the  shores  of  the 

*  Lazarus   Zetznerus,     Theatrum  Chernicum  Argentorati,    1659,    de 
Practica  Magistri  Odomari,  vol.  iii.,  p.  169. 


20  Occurrences. 

Baltic,  and  there  spent  nearly  eighteen  months,  experi- 
menting upon  sea- water,  without  any  result.^  Gabriel  de 
Chataigne,  the  Grand  Almoner  of  Louis  XIII.,  seems  to 
have  been  more  fortunate,  for  he  states  that  he  himself 
saw  transmutation  effected  by  a  stone  prepared  with  sea 
salt,f  and  some  report  of  this  statement  no  doubt  inspired 
Becher,  in  the  proposal  which  he  made  in  1669  to  the 
States  General  of  Holland,  to  turn  the  dunes  into  gold, 
his  offer,  according  to  him,  after  the  favourable  report  of  a 
committee  of  chemists,  being  only  rejected  on  account  of 
the  low  state  of  the  Dutch  exchequer.^ 

Those  curious  in  such  survivals  will  find  a  series  of  ex- 
periments, intended  to  show  the  possibility  of  the  transmu- 
tation of  metals,  set  out  at  length  in  the  report  of  a  M.  C. 
Theodore  Tiffereau  to  the  French  Academy  in  1854.1  If 
M.  Tiffereau  really  did  succeed  in  producing  traces  of  gold 
by  any  such  process  as  he  describes,  his  success  would  seem 
to  be  due  to  the  fact  that  he  employed  sea-salt  as  one  of 
his  ingredients. " 

The  theory  of  the  formation  of  veins,  and  the 
occurrence  of  gold  therein,  also  in  unstratified  rocks,  &c., 
although  deeply  interesting,  is  outside  the  purpose  of 
this  inquiry,  as  is  also  any  record  of  observations 
concerning  shoots  of  gold  in  veins,  saddle-back  veins, 
&c.,  for  the  reason  that  to  touch  upon  these  ques- 
tions would  only  result  in  incompleteness,  and  to 
enter  thoroughly  into  an  investigation  would  lead  into 
so  many  by-paths,  as  to  extend  these  notes  far  beyond 
their  intended  limit. 

*  Ibid.,  Bernard!  Trevisani  de  Alchemia  Liber,  vol.  i.,  p.  686. 
t  L'Alchimie  et  les  Alchiinistes  par  Louis  Figuier,  Paris,  1856. 
£  Physica  subterranea  Becherii 


Remarks.  21 


CHAPTER  III. 

REMARKS  ON  THE  PROCEDURE  OF  LATE  YEARS. 

WITHOUT  in  any  way  attempting  to  investigate  the 
history  of  gold,  it  may  be  mentioned  that  from  the 
earliest  times  of  which  there  is  any  record — apart  from 
the  practice  of  smelting — two  main  principles  were 
followed  out  in  endeavouring  to  collect  gold,  no  matter 
in  what  form  it  was  discovered.  These  were  : 

1st.  Recognising  the  relative  gravity  of  the  metal, 
crushed  ore  was  subjected  to  the  action  of  a 
stream  of  water,  in  order  that  the  force  of  its 
gravity  might  work  the  golden  salvation  sought, 
by  bearing  the  metal  to  the  bottom  of  the  stream, 
and  keeping  it  there  until  all  else  had  been 
carried  off. 

2nd.    The    affinity   between    gold     and    mercury  was 

recognised  and  it  was    believed   that  the   latter 

possessed    the   property    of    absorbing     all    gold 

particles,   and  also  of  rapidly   re-forming   into    a 

mass,   even  after   being   broken  up    into   minute 

globules  by  shaking  or  friction  ;  for  this  reason 

mercury  was  put  into  a  mill  with  gold  ore,  and 

either  crushed  with  the  ore  or  agitated  through  it. 

In  ancient  Egypt,  many  centuries  before  the  Christian 

era,   gold   ores  were  crushed    between  stones,  and    the 

powdered  rock  and  metal  afterwards  washed  by  a  stream 

of  water  over  an  inclined  plane,  when  all  rock  particles 


22  Remarks. 

were  thus  swept  away,  any  gold  remaining  was  secured. 
T"ery  old  records  also  point  to  the  addition  of  mercury 
as  an  agent  to  facilitate  the  collection  of  gold  particles  ; 
for  this  purpose  it  was  either  placed  below  the  stream  of 
water,  or  agitated  throughout  the  mass  of  ore. 

As  it  is  with  the  collection,  not  the  discovery  of  gold, 
that  these  notes  will  chiefly  deal,  it  will  suffice  to  draw 
attention  to  modern  practice  and  developments  since  the 
discoveries  of  gold  in  California  in  1848  and  Australia  in 
1851.  One  of  the  most  remarkable  features  noticeable 
when  dealing  with  this  subject  is,  that  although  decades 
of  centuries  have  passed  since  history  tells  of  the  methods 
employed  in  saving  gold,  the  self-same  principles  are  still 
perpetuated,  as  those  which  we  may  imagine  to  have 
been  adopted  by  pre-historic  man.  To-day,  in  the  great 
majority  of  countries  and  places  where  gold  is  mined,  the 
two  main  principles  mentioned  comprise  almost  all  the 
cunning  brought  to  bear  upon  this  important  problem  ; 
•certainly,  modifications  in  procedure  have  been  introduced, 
but  these  chiefly  tend  to  developments  in  crushing  rocks, 
and  the  fact  remains,  that  every  piece  of  gold  saved 
must  possess  the  inherent  quality  of  withstanding  a  rush 
of  water,  sinking  through  it  and  amalgamating  with 
mercury,  otherwise  it  will  be  washed  away  and  practi- 
cally lost. 

A  glance  at  the  practice  of  miners'  of  forty  years  ago 
may  be  of  interest.  As  soon  as  a  man  abandoned  prosaic 
modes  of  obtaining  a  livelihood  and  took  to  the  life  of  a 
gold  seeker,  he  then  seemed  to  become  imbued  with 
strange  characteristics ;  a  self-conscious  air  of  heroism 
seemed  to  surround  him.  As  this  increased,  so  vanished 
all  sense  of  prudence  necessary  to  successfully  regulate 
everyday  life  ;  thrift,  forethought,  and  reason,  gave  place 


Remarks.  23 

to  a  wild  infatuation  for  getting  gold,  without  one 
thought  of  ever  keeping  it.  The  history  of  how  the 
trader  enriched  himself  by  taking  advantage  of  the 
swaggering  independence  and  prodigality  of  the  miner, 
reads,  wherever  written,  as  though  it  were  the  work  of  a 
clever  romancer,  instead  of  a  plain  statement  of  facts. 
This  strange  mannerism  seemingly  not  born  of  race  or 
country,  is  the  marked  characteristic  which  has  shown 
itself,  and  will  no  doubt  show  itself  again,  whenever 
and  wherever  new  gold  discoveries  are  made.  It  follows 
as  a  natural  consequence  that  without  being  so  born,  a 
race  of  men  are  bred  who  will  neither  be  taught  nor 
learn  to  attend  to  and  conserve  their  own  interests. 
Amongst  miners  there  has  been  no  greater  object  of 
general  derision  than  a  man  preaching  against  their 
accepted  methods ;  to-day  it  is  almost  the  same. 

The  miner  is  hard  to  convert;  he  is  a  conservative  of 
the  conservatives  in  the  devotion  with  which  he  guards 
his  rule  of  thumb  fallacies,  but  unfortunately  his  con- 
servatism does  not  apply  to  the  saving  of  gold  ;  in  this 
respect  he  may  be  considered  a  liberal  of  the  most  pro- 
nounced type.  When  the  miners  of  thirty  years  ago 
found  gold  in  earth  and  gravel,  they  continued  the 
practice  adopted  by  miners  in  dimly  remembered  ages ; 
that  which  was  too  small  to  pick  out  they  attempted  to 
save  by  setting  a-  stream  of  water  to  wash  away  the  earth 
and  stones  with  which  it  was  mixed ;  it  fulfilled  its 
mission  by  carrying  off  all  particles  which  had  not 
sufficient  weight  to  withstand  the  flow  of  water.  When 
water  was  scarce  the  "dirt"  was  put  in  cloths  or 
blankets,  then  shaken  high  in  the  air,  in  the  belief  that 
the  wind  would  blow  away  everything  light.  *  These 

*  As  an  illustration   of  this  :  In  the  waterless  gold-producing  dis- 


24  Remarks. 

slap-dash  methods  having  soon  exhausted,  at  any  rate 
so  far  as  to  satisfy  the  miner,  the  then  discovered 
finds,  therefore,  the  adventurers  sought  other  deposits- 
and  turned  their  attention  to  the  gold  contained  in  lodes 
and  rocks.  They  crushed  these  rocks  and  applied  to  the 
crushings  the  self-same  principles  as  before,  with  very 
much  the  same  result. 

The  sense  of  sight  was  of  all  others  the  one  most 
trusted;  that  which  could  be  seen  by  the  unaided  eye  was 
sought  after  and  recovery  attempted;  that  which  was  not 
seen,  though  demonstrated  by  a  magnifying  glass  or 
assay,  was  thought  of  little  account,  and  treated  accord- 
ingly. Various  theories  were  invented  by  which  losses 
might  be  accounted  for;  certain  ores  were  found  which 
would  not  give  the  gold  visible  in  them,  and  some  bright 
genius  hit  upon  the  terms  "refractory,"  "rebellious,"  and 
"  rusty,"  and,  in  cases  where  very  fine  gold  occurred,  the 
term  "float  gold."  The  amount  of  consolation  afforded  for 
years  past  to  the  miner  by  the  invention  of  these  terms 
has  indeed  been  infinite,  they  are  used  over  and  over 
again  with  most  satisfying  effect  when  the  mill  returns 
fail  to  give  anything  like  an  approach  to  assay  values. 
In  fact,  in  many  cases  whole  districts  showing  by  assay 
to  be  very  rich  in  gold,  have  been  entirely,  or  almost 
entirely,  abandoned  because  of  the  difficulty  experienced 
in  securing  the  gold.  This  has  resulted  from  the  per- 
sistent endeavours  to  continue  in  the  long-trodden  paths, 

tricts  of  New  South  Wales,  on  any  windy  day,  rows  of  miners  may  be 
seen  throwing  high  in  the  air  the  "dirt "  out  of  their  tin  dishes,  and 
so  separating  a  large  percentage  of  the  metal  from  its  surroundings. 
To  those  not  versed  in  the  question,  this  may  seem  a  very  ridiculous 
proceeding,  but  in  reality,  though  perhaps  slower,  it  is  not  such  a 
wasteful  method  as  hydraulic  separating;  the  question  of  collection 
by  winnowing  will  be  dealt  with  in  another  chapter. 


Remarks.  25 

and  apply  to  every  class  of  ores  the  principles  of  con- 
centration in  a  stream  of  water,  and  amalgamation  under 
similar  conditions  with  mercury.  In  ordinary  avocations 
of  life  a  tradesman  would  be  considered  as  a  species  of 
lunatic  if  he  attempted  to  carry  out  watchmakers'  work 
with  blacksmiths'  tools,  yet  the  miner  has  as  widely  dif- 
ferent propositions  put  before  him  as  those  existing  between 
the  trades  mentioned,  and  still  he  persists  in  working 
with  only  the  one  old-fashioned  and  scanty  kit  of  tools. 

Since  set  moving  by  this  later  influx  of  gold  to  the 
world's  circulation,  places  and  things  have  gone  ahead 
very  rapidly,  and  the  same  standard  by  which  we  judge 
the  miner  of  forty  years  ago,  should  not  be  applied  to-day; 
what  was  thoughtless  and  foolish  then  is  now  very  much 
like  culpable  ignorance.  The  old-time  miner  had  little 
or  no  option,  appliances  were  difficult  to  obtain, 
costly  when  obtained,  and  the  process  of  getting  almost 
invariably  resulted  in  much  chafing  delay.  Such  is  not 
the  case  at  present;  there  are  few  parts  of  the  world  to 
which  appliances  cannot  now  be  sent  in  the  same  number 
of  weeks  that  formerly  occupied  months  in  transit ; 
freights  and  prices  of  machinery  are  much  less.  The  sub- 
ject has  also  been  studied  and  written  upon,  and  knowledge 
is  to  be  had  for  the  picking  up  ;  all  through  these  years, 
men  of  common  sense,  and  men  of  the  highest  scientific 
attainments,  have  spoken  and  written  of  the  wrongfulness 
and  wastefulness  of  the  methods  in  vogue ;  every  opinion 
herein  expressed  is  but  an  echo  of  what  has  been  written 
and  spoken  over  and  over  again.  But  the  policy  of 
mining  men  has  ever  been,  "  Take  what  we  can  get  easily, 
and  don't  bother  about  that  which  is  difficult,"  together 
with  the  often-expressed  sentiment,  "  Oh,  we  are  getting 
enough."  The  average  miner  of  to-day  will  speak  as 


26  Remarks. 

though  his  voice  were  the  voice  of  a  phonograph  that 
had  been  laid  by  for  forty  years — had  such  a  contrivance 
been  then  invented. 

Of  late  years,  more  deadly  by  far  than  the  miner  as  an 
opponent  to  the  advancement  of  the  science  of  metallurgy, 
is  the  "  mining  expert,"  who  thrives  in  the  quarters  of 
large  cities  where  share  and  stock  dealing  is  carried  on. 
Of  course  there  are  notable  and  honourable  exceptions, 
but  the  trouble  is  that  any  one  and  every  one  is  free  to  dub 
himself  a  Mining  Engineer,  consequently  the  true  and  the 
false,  as  far  as  name  is  concerned,  trade  under  the  same 
sign.  Very  frequently  the  limited  information  possessed 
by  many  of  these  scientific  gentlemen  is  supplemented 
by  a  facility  for  compiling  estimates  from  picked  samples 
and  fanciful  assays,  rendering  them  invaluable  allies  to  a 
certain  class  of  company  promoters  and  their  pestilent 
horde.  It  is  no  light  and  easy  task  for  business  men  and 
directors  of  mining  ventures  to  discriminate  without  pre- 
vious knowledge  between  the  sound  men  and  the  "frauds" 

o 

who  make  up  this  body,  for  to  the  non-technical  mind  a 
semblance  of  great  knowledge  is  frequently  conveyed  by 
a  few  scientific  terms  aptly  introduced  in  conversation. 

There  is  yet  another  class  that  tend  to  retard  advance- 
ment; these  are  a  large  percentage  of  the  fledglings  who, 
without  any  practical  knowledge,  are  turned  out  of 
mining  schools  and  similar  institutions.  They  arrive 
on  the  goldfields  brimful  of  enthusiasm  and  a  mass  of 
unassimilated  information,  without  sufficient  discrimina- 
tion or  capability  to  put  it  to  practical  use.  They  con- 
front the  miner  with  what  are,  in  effect,  useless  and  new- 
fangled theories,  therefore  their  efforts  to  instruct  him 
invariably  ends  in  dismal  failure,  and  weds  him  more 
firmly  to  the  methods  of  the  ancients. 


Remarks.  27 

It  should  be  remembered  by  those  who  deal  with 
the  subject,  that  it  is  the  obsolete  traditions  and  the 
manner  in  which  they  are  clung  to  that  are  alone  deserving 
of  censure.  The  amount  of  energy  displayed  and  the 
degree  of  perfection  reached  by  the  miner  is,  in  many 
instances,  deserving  of  unmeasured  praise.  Doubtless 
in  a  great  measure  he  has  been  forced  into  this  by  the 
progressiveness  and  ability  of,  and  competition  between, 
machinery  manufactures.  In  alluvial  and  hydraulic 
mining  especially  the  improvement  is  marked;  by  toil  and 
care  the  gold  miner  is  now  enabled  to  work  remunera- 
tively by  taking  out  what  approach  millionth  parts  of 
the  mass  with  which  he  deals ;  results  unparalleled  by 
the  records  of  any  other  metal  worker.  A  worker  in 
tin,  iron,  copper,  lead,  and  other  ores  thinks  it  well  when 
only  tenths  and  hundreds  are  run  to  waste,  whereas 
the  gold  miner  must,  practically,  in  every  instance, 
remove  nine  hundred  and  ninety-nine  and  a  frac- 
tional part  per  thousand  of  the  whole  body  of  ore 
before  he  obtains  what  he  seeks.  For  instance,  with 
stuff  mined  and  raised  from  as  deep  as  200  ft.  and  300  ft. 
below  the  surface,  he  can  by  the  collection  of  from  two  or 
three  pennyweights  of  gold,  pay  a  dividend;  these 
two  or  three  pennyweights — 48  to  72  grains — are 
the  aggregated  weight  of  minute  particles  of  metal 
disseminated  throughout  15,680,000  grains  in  weight 
of  one  ton  of  dirt.  Where  the  principle  of  hydraulic 
mining  can  be  adopted,  he  has  made  as  low  a  return  as 
one  and  a  half  grains  (3  cents^)  collected  from  15,680,000 
grains,  a  paying  concern ;  these  are  results  brought  about 
by  the  working  of  companies  adopting  the  most  advanced 
methods. 

*  Egleston's  "Gold  and  Silver." 


28  Remarks. 

But  with  mining,  as  in  everything  else,  the  rapid 
diffusion  of  knowledge  is  dimming  the  halo  of  romance 
which  generally  surrounds  distant  and  unknown  avoca- 
tions. The  typical  miner  is  gradually  and  surely  be- 
coming extinct,  his  trade  is  now  dolefully  prosaic ;  by 
shrewd  investors  it  is  beginning  to  be  regarded  as  a  legiti- 
mate sphere  wherein  to  embark  capital ;  thus  combination 
and  capital  have  made  the  worker  a  "  wages  man."  The 
greater  number  of  the  most  valuable  mining  pro- 
perties known,  are  in  the  hands  of  companies,  many 
of  which  are  managed  by  business  men  who  are  prepared 
to  apply  to  this  business  the  same  economical  principles 
as  those  by  which  all  other  successful  undertakings  are 
guided.  Such  men  are  ready  and  doubtless  anxious  to 
listen  to  reason,  provided  the  reason  be  sound  and  stated 
with  sufficient  distinctness. 


Losses.  29 


CHAPTER  IV. 

LOSSES. 

To  generalise  about  antediluvian  methods  of  working, 
about  the  enormity  of  ensuing  losses,  or  the  obduracy  and 
ignorance  of  miners  and  those  connected  with  them,  will 
never  make  clear  the  fundamental  errors  forming  the 
framework  of  most  of  the  gold-extracting  methods  in 
general  use.  Facts  and  figures,  the  reason  why,  and 
evidence  to  support  it,  must  be  adduced  to  prove  the 
truth  of  every  charge  against  the  time-worn  customs 
assailed;  therefore,  with  this  course  in  view,  the  questions 
and  their  answers  will  be  classified  as  closely  as  possible, 
although  in  the  majority  of  instances  the  causes  of  losses 
are  so  closely  associated  and  run  one  into  the  other  that 
no  distinct  dividing  line  can  be  drawn  between  them. 

These  losses  will  be  dealt  with  separately  under  three 
heads  and  do  not  include  problems  in  alluvial  mining  : 

A.  FREE  MILLING  ORES. 

B.  REFRACTORY  ORES. 

C.  MERCURY. 

FREE  MILLING  ORES  are  those  which  yield  their  gold, 
when  subjected  to  the  processes  of  crushing,  and 
amalgamating  with  mercury. 

REFRACTORY  ORES  are  those  which  contain  "fold  in  such 

o 

association  as  to  cause  much  loss  in  the  ordinary  process 
of  crushing  and   amalgamating,  or  where  other  minerals 


30  Losses. 

are  present  with  gold,  which,  by  'their  physical  and 
chemical  properties,  act  deleteriously  on  mercury  and 
render  amalgamation  difficult. 

A.    LOSSES  OF  GOLD  IN  FREE  MILLING  ORES. 

1.  Fine  gold  held  in  suspension  by  water  and  carried 

down  stream. 

2.  Fine  gold  particles  encased  or  attached  to  pieces  of 

rock  and  carried  into  tailings  or  down  stream. 

3.  Clayey  ores  make  the  battery  water  very  muddy 

and  holds  mechanically  fine  gold  particles  in  sus- 
pension, until  deposited  in  tailings  or  down  stream. 
4i  yWhen  any  artificial  conditions  arise,  whereby  certain 
substances  may  find  their  way  into  crushing 
mills  or  other  appliances,  practically  insuperable 
difficulties  may  be  occasioned;  similar  results  may 
arise  from  natural  films  coating  the  gold.  Anything 
which  creates  films  and  prevents  perfect  contact 
between  the  metals,  renders  the  gold  non-amalga- 
mable,  therefore  all  but  the  heavier  particles  will 
be  swept  into  the  tailings  or  down  stream. 

5.  Though  gold  be  in  a  perfect  condition  for  amalgama- 

tion, impure  mercury  will  not  act;  in  such  a  case,  al] 
but  the  heavier  particles  would  be  washed  into 
tailings  or  down  stream. 

6.  Though  both  gold  and  mercury  be  in  a  perfect  con- 

dition for  amalgamation,  and  have  amalgamated, 
excessive  stamping  in  batteries,  agitation  or  grind- 
ing action  in  the  machinery  and  other  causes  bring 
about  granulation  of  the  amalgam  and  leave  it  in 
a  condition  to  be  readily  carried  off  by  water,  either 
into  tailings  or  down  stream. 


Losses.  31 

B.     Loss  OF  GOLD  IN  REFRACTORY  ORES. 

1.  Fine  gold  held  in  suspension  by  water  and  carried 

down  stream. 

2.  Fine  gold  attached  to  pieces  of  rock  or  encased  in 

pieces  of  base  mineral  and  carried  into  tailings  or 
down  stream. 

3.  Base    minerals    associated    with    the    gold    invari- 

ably coat  the  surfaces  of  gold  particles  to  a  large 
percentage  of  the  total  quantity  contained  in  the 
ore,  and  also  give  rise  to  complicated  chemical 
reactions ;  the  effect  of  either  or  both  actions 
is  to  prevent  amalgamation,  and  allow  the  gold 
to  be  carried  into  tailings  or  down  stream. 

4.  The  partial  decomposition  of  base  minerals  in  refrac- 

tory ores  produce  acidulated  water  and  its  train 
of  attendant  evils  which  act  deleteriously  in 
amalgamation,  causing  granulation  of  the  mercury 
(sickening  or  flouring)  which  prevents  the  particles 
re-uniting,  leaving  them  in  a  condition  to  be 
readily  carried  by  water ;  gold,  amalgam,  and 
mercury  are  then  in  the  best  possible  condition  to 
be  carried  off  by  the  water,  either  into  the  tailings 
or  down  stream. 

5.  The  mechanical  effect  of  heavy  mineral  particles  in 

the  ore,  falling  through  the  stream  of  water, 
prevent  contact  between  the  amalgamating  sur- 
faces and  eventually  cut  off  and  clean  the  amalgam 
and  mercury  from  the  plates,  causing  loss  of  gold, 
mercury,  and  amalgam. 

Most  of  the  sources  of  loss  enumerated  above  are 
common  to  both  classes  of  ore ;  they  are  not  twice 
specified  in  every  case,  in  order  to  reduce  repetition. 


32  Losses. 

C.  LOSSES  OF  MERCURY. 

Continuous  stamping,  agitation,  or  grinding  causes 
mercury  to  form  into  minute  globules  ;  these  have 
the  property  of  collecting  fine  films  of  matter  and 
air  particles  on  their  surface,  which  reduce  their 
relative  weights,  preventing  their  reunition,  and 
are  thus  in  a  condition  to  be  readily  carried  off  by 
water  into  tailings  or  down  stream. 

o 

The  following  record  of  experiments  and  observations 
in  actual  practice  will  prove  conclusively  that  the  fore- 
going dangers  are  not  imaginary,  nor  are  they  magnified. 

From  every  part  of  the  world  where  gold  mining  is 
carried  out,  the  tale  is  the  same,  when  told  by  men  who 
investigate  the  actual  condition  of  things. 

Under  the  various  heads,  already  detailed  and 
numbered,  the  causes  of  losses  will  be  dealt  with  in 
greater  detail  and  the  result  of  experiments  given. 

A  1.   Fine  gold  held  in  suspension  by  water  and 
carried  down  stream. 

At  Spring  Gully  Mines  Thornborough  Hodgkinson 
Goldfield  Queensland  when  dealing  with  an  ordinary 
clean  white  gold-bearing  quartz,  the  existence  of  a  con- 
tinued and  regular  loss  was  observed  between  the  actual 
returns  from  ore,  milled  in  the  ordinary  stamper  battery, 
with  the  crushings,  afterwards  treated  by  the  most 
approved  amalgamating  methods,  and  the  estimated 
.  returns,  calculated  upon  assay  values.  In  order  to 
determine  in  a  practical  manner  the  cause  of  this  loss, 
the  following  experiment  was  carried  out :  Two  five-head 
batteries,  side  by  side,  were  fed  equally,  and  at  the  same 
time,  from  a  heap  of  quartz  weighing  100  tons,  the 


Losses.  3  3 

in  both  cases  being  passed  over  amalgamating  plates. 
In  one  case  it  was  led  into  a  pit,  from  which  there  was 
the  usual  and  constant  stream  of  water  overflowing  from 
the  surface  ;  in  the  other  case,  with  a  similar  quantity 
of  water,  it  was  led  into  a  pit  of  500-ton  capacity, 
from  which  no  water  was  allowed  to  flow  from  the  surface, 
the  surplus  having  to  filter  through  the  pulp  and 
escape  from  the  bottom.  In  both  cases  the  yield  from 
the  ore,  of  the  gold  caught  in  the  battery  and  on  the 
plates,  was  1  oz.  10  dwts.  per  ton.  The  tailings  from  both 
pits  were  then  carefully  sampled  and  assayed  :  in  the  first 
case,  where  the  surface  water  escaped,  the  returns  were 
constant  to  about  7  dwts.  per  ton ;  in  the  second  case,  where 
the  water  filtered  through  the  pulp  or  tailings,  the  returns 
were  constant  to  about  15  dwts.  per  ton.  This  showed  a 
loss  of  8  dwts.  per  ton  of  gold  carried  off  by  water  ;  over 
25  per  cent,  of  the  quantity  saved  by  the  original  treat- 
ment, in  money  value  a  loss  of  30s.  per  ton  (roughly).f 

At  the  Mount  Morgan  mine  in  Queensland,  already 
described,  the  ore  is  one  generally  regarded  by  mining 
men  as  a  free  milling  ore,  namely,  with  an  entire  absence 
of  such  ingredients  as  sulphur,  arsenic,  antimony,  &c., 
Although  in  individually  minute  particles,  the  gold  was 
perfectly  clean,  yet  as  a  matter  of  fact,  it  proved  as 
"refractory"  and  as  difficult  of  treatment  as  one  most 
highly  charged  with  mineral  sulphides  or  arsenides. J  As 
before  stated,  the  matrix  is  a  silicious  brown  iron  ore 
varying  from  nearly  pure  silica  to  true  limonite  ;|| 

*  Crushed  rock  and  metal. 

t  Mr.  George  Latta,  in  New  South  Wales,  as  far  back  as  1865, 
perhaps  earlier,  followed  the  same  procedure  on  a  small  scale  in 
obtaining  assay  samples. 

t  See  result  of  Dr.  Leibius'  experiments  quoted  on  page  36. 

I!  Brown  iron  ore. 


34  Losses. 

stalactitic  masses  frequently  occur.  Some  of  these 
stalactitic  formations  were  cut  across  and  polished, 
which  showed  that  they  were  composed  of  a  number  of 
concentric  rings  formed  by  solutions  of  varying 
richness ;  some  of  these  rings  were  nearly  pure 
silica,  others  almost  pure  limonite,  and  the  clearer  rings 
showed  most  gold,  although  in  some  cases  the  limonite 
was  extraordinarily , rich.  If  a  piece  of  this  brown  iron 
ore  was  put  into  hydrochloric  acid  and  left  undisturbed 
for  a  few  days,  the  iron  would  all  be  dissolved  out,  and 
leave  as  a  residue  a  friable  spongy  mass,  composed  of  almost 
pure  silica,  the  same  shape  and  nearly  the  same  size  as 
before,  in  which  bright  flakes  of  gold,  like  minute  fragments 
of  gold  leaf,  might  be  seen.  If  this  silica  was  squeezed  in 
the  fingers  no  grit  of  any  kind  could  be  felt ;  it  was 
as  though  a  paste  was  being  squeezed  or  pressed. 

In  the  early  attempts  to  treat  this  ore  great  difficulties 
and  losses  presented  themselves.  The  contents,  by  assay 
returns,  varied  from  8  oz.  to  1 0  oz.  of  gold  per  ton  of  ore. 
The  ore  was  milled  and  amalgamated  in  the  most  careful 
manner  in  stamper  batteries  and  other  machines,  and  the 
tailings  ground  in  pans  with  mercury  until  they  were  an  im- 
palpable powder,  the  very  friable  nature  of  the  ore  render- 
ing this  comparatively  easy.  The  returns  after  such  treat- 
ment were  about  2  oz.  to  the  ton,  and  the  tailings  assayed 
from  5  oz.  to  6  oz.,  and  the  loss  went  on  until  the  pro- 
prietors had  accumulated  a  heap  of  tailings,  say,  20,000 
tons,  giving  by  assay  about  the  before-mentioned  average. 

Scarcity  of  water  prevailed  in  the  district ;  the  hill 
wherein  the  mine  is  situated  was  especially  waterless  ; 
therefore  the  battery  water  was  used  over  and  over 
again,  it  soon  became  a  rusty  colour  and  contained  a 
great  quantity  of  water-borne  gold.  After  all  the  mud 


Losses.  35 

and  slimes  had,  as  much  as  possible,  been  removed  from 
the  water  by  settling  pits,  the  engine  boilers  were  fed  by 
water  pumped  from  the  dam  nearly  500  ft.  below  the 
tailing  heap.  The  boilers  soon  became  coated  with  scale, 
and  mud  settled  on  the  bottom;  when  they  were  cleaned 
and  the  scale  treated,  a  return  of  gold  was  obtained 
equal  to  1 1  oz.  per  ton  of  scale. 

On  account  of  the  water  difficulty  dry  crushing  was 
introduced  ;  this  was  carried  on  in  a  closed  building.  The 
dust  in  the  building  was  held  in  suspension  by  almost 
still  air,  and  some  which  escaped  through  crevices  in  the 
structure  and  settled  on  ledges  or  projections  was  after- 
wards collected  and  assayed,  and  found  in  many  instances 
to  give  a  higher  value  than  the  average  of  the  ore. 
Some  of  this  dust  was  put  in  a  pan  and  the  oxide  of  iron 
dissolved  by  hydrochloric  acid,  then  the  gold  which  it 
contained  could  be  seen  like  yellow  distemper  paint  on  the 
bottom  of  the  dish.  Vat  chlorination,  commonly  known  as 
the  "Plattner"  system,  was  then  introduced;  treatment  by 
this  means  was  even  a  greater  failure  than  amalgamation. 

Parcels  of  the  ore  were  then  shipped  to  the  German 
Government  smelting  works,  to  England,  and  to  metal- 
lurgists of  the  highest  repute  in  San  Francisco,  so  that 
the  difficulty  might  be  solved.  By  smelting,  the  Germans 
were  able  to  get  adequate  returns,  but  owing  to  the 
highly  silicious  nature  of  the  ore  they  could  only  use 
it  in  small  quantities,  when  it  would  flux  with  other 
ores,  and  consequently  would  guarantee  no  regular  treat- 
ment in  bulk ;  the  negotiations  therefore  came  to  nothing. 
In  England  the  same  result  followed,  and  the  investiga- 
tions in  San  Francisco  did  not  result  in  a  solution  of  the 
difficulty. 

In  a  paper  read  by  Dr.  Liebius  of  the  Sydney  Mint, 


36  Losses. 

before  the  Royal  Society  of  New  South  Wales  in  1884, 
the  following  record  is  given  of  his  struggle  to  solve  this 
metallurgical  puzzle. 

Locke,  in  his  work  on  gold  published  in  1882,  says  no  gold  has  yet 
been  found  in  nature  unalloyed  with  silver.  Yet  this  gold  from  the 
Mount  Morgan  Mine,  of  which  since  February  last  already  over 
10,000  oz.  have  been  received  as  retorted  gold  at  the  Sydney  Mint,  is 
found  to  be  free  from  silver — a  minute  trace  excepted.  I  have  brought 
some  of  this  retorted  gold  rolled  out  very  thin  to  show  its  toughness. 
It  assays  99.7  per  cent,  of  gold  ;  the  rest  is  copper,  with  a  trace  of 
iron.  Gold  assaying  99.7  per  cent,  is  worth  4:1.  4s.  8d.  per  oz.  Gold 
from  the  same  mine  received  at  the  Mint  assayed  as  high  as  99.8  per 
cent.  It  is,  as  far  as  I  know,  the  richest  native  gold  hitherto  found. 
A  not  less  interesting  though,  less  satisfactory  fact  is  this  :  that  only 
about  half  the  gold  is  extracted  by  the  ordinary  quartz- crushing  and  amal- 
gamating machinery.  The  tailings  which  are  being  stored  are  said  to 
contain  as  much  gold  as  is  saved,  and  as  they  will  be  subjected  to 
treatment  at  a  future  date,  the  result  will  be  highly  advantageous  to 
the  owners.  Having  the  small  quartz-crushing  machinery  erected  at 
the  Sydney  Mint  under  my  charge,  I  have  had  an  opportunity  of  test- 
ing this  fact.  In  November  last  (1883)  we  received  through  Mr.  Hall, 
of  Sydney,  458  Ib.  of  this  ferruginous  quartz,  part  of  it  consisting  of 
picked  stone.  It  was  carefully  crushed  and  amalgamated  in  the  Chilian 
mill  with  240  Ib.  mercury.  Thus  7.44  oz.  of  gold  assaying  991.5 
were  extracted.  Another  lot  weighing  174  Ib.  was  similarly  treated 
and  12.12  oz.  of  gold  extracted,  assaying  998.2.  Thus  lot  No.  1  gave 
gold  at  the  rate  of  39.32  oz.  standard  per  ton  of  quartz,  while  lot  No.  2 
gave  gold  at  the  rate  of  169.86  standard  per  ton  of  quartz.  In  lot  No.  1  at 
the  rate  of  46  oz.  2  dwts.  12  grs.  per  ton  was  left  in  the  tailings,  while  in 
lot  2  the  tailings  assayed  64  oz.  5  dwts.  18  grs.  of  gold  per  ton.  Both 
lots  of  tailings  were  now  mixed  and  passed  for  two  or  three  hours  in  the 
Chilian  mill  with  240  Ib.  clean  retorted  mercury.  Only  1.66  ozs.  of 
gold,  assaying  981,  were,  however,  obtained  by  this  treatment.  The 
tailings  were  dried  and  found  to  weigh  476  Ib.,  containing  gold  at  the 
rate  of  41  oz.  13  dwts.  16  grs.  per  ton — or,  in  about  476  Ib.  tailings 
no  less  than  8  oz.  17  dwts.  3  grs.  of  gold.  I  have  brought  some  of 
those  tailings  here.  Under  the  microscope  there  is  no  gold  visible.  I 
thought  that  if  the  oxide  of  iron  were  removed,  by  boiling  the  tailings 
in  hydrochloric  acid,  and  the  solution  filtered  off,  the  gold  might  more 
readily  be  discernible  in  the  boiled-out  residue.  I  found,  however,  that 
this  was  not  the  case,  and  that  1000  grains  of  tailings  thus  boiled  in 


Losses.  37 

strong  hydrochloric  acid,  by  which  about  20  per  cent,  were  dissolved, 
gave  me  only  0.73  grains  of  gold,  the  same  as  when  boiled  with  nitric 
acid.  The  loss  of  gold  by  boiling  in  hydrochloric  acid,  was  no  doubt 
due  to  the  action  of  this  acid  upon  manganese  in  the  ore,  whereby 
chlorine  gas  was  formed,  a  ready  solvent  for  gold.  That  the  ordinary 
amalgamating  Chilian  mill  did  not  extract  all  the  gold  in  this  stone,  I 
can  only  attribute  to  the  supposition  that  the  oxide  of  iron  has  literally 
coated  some  of  the  fine  gold,  thus  preventing  it  coming  in  contact  with 
the  mercury. 

In  touching  upon  the  action  of  chlorine  it  is  astonishing 
to  find  how  close  Dr.  Liebius  got  to  the  ultimate  solution 
of  the  question  before  giving  the  matter  up  as  a  bad  job. 

As  a  last  resource,  when  the  "  practical  man "  of 
Australia  proved  a  failure — as,  indeed,  he  usually  does 
in  all  countries  when  difficult  problems  arise — some  of 
the  ore  was  sent  to  the  Technological  Museum,  Mel- 
bourne, which,  in  the  Colonies  by  those  not  too  proud  to 
ask  for  information  at  home,  is  regarded  as  the  practical 
encyclopedia  for  all  scientific  questions.  Mr.  J.  Cosmo 
Newbery,  the  chief  of  the  institution,  examined  it,  and  in 
his  experiments  was  assisted  by  Mr.  Claude  Vautin,  who 
was  there  working  some  other  experiments  at  the  time. 
After  trying  chlorination  and  the  most  accurate  of  known 
amalgamating  methods,  that  of  boiling  slimes  in  a 
cauldron  with  mercury — both  of  which  processes  resulted 
in  failure — a  very  critical  examination  was  made  of 
the  nature  of  the  ore.  It  was  then  found  to  be, 
even  when  divided  into  the  most  impalpable  dust,  a 
hydrous  oxide  of  iron*  with  hydrous  silica. t  When 
de-hydrated  by  heat,  the  grains  became  more  friable  and 
gave  up  most  of  their  gold  to  ordinary  amalgamation, 
the  tailings  assaying  only  from  10  dwts.  to  20  dwts.  per 
ton,  instead  of  from  5  oz.  to  6  oz.  of  gold  as  before.  When 

*  A  combination  of  iron  rust  and  water, 
t  A  combination  of  water  and  silica. 


38  Losses. 

the  de-hydrated  ore  was  subject  to  the  ordinary  vat,  or 
"  Plattner "  chlorination,  the  extraction  was  practically 
perfect,  the  quantity  left  in  being  only  2  or  3  grains  to 
the  ton.  So  far  all  was  well,  but  a  difficulty  arose  from 
the  nature  of  the  ore  which  necessitated  the  abandonment 
of  the  "  Plattner "  process.  The  ore  being  so  friable, 
an  enormous  proportion  of  slime  was  produced  by 
the  crushing  mills  which  prevented  almost  entirely 
the  permeation  of  chlorine  gas  and  rendered  filtration 
practically  impossible;  this  subsequently  led  to  a 
modified  method  now  known  as  the  Newbery-Vautin 
chlorination  process.  A  peculiar  feature  in  the  roasting 
of  this  ore  was  noticeable,  namely  :  if  some  finely  ground 
dry  ore  was  placed  in  a  pan  and  heated,  it  soon  began  to 
bubble  just  as  boiling  water,  and  an  innumerable  number 
of  small  volcano-like  cones  were  formed  by  the  de-hydra- 
tion  ;  if  this  pan  was  knocked  or  tilted  ever  so  little,  the 
whole  mass  became  quick  and  ran  like  water  into  the  fire 
almost  instantly.  This  property  rendered  the  calcination 
of  the  slimes  and  finely  crushed  ore  a  matter  of  extreme 
difficulty  in  the  ordinary  furnace. 

This  class  of  ore  is  by  no  means  rare;  it  is  in  fact  an 
ironstone  gossan,  and  the  ores  forming  the  outcrop  of 
almost  every  lode,  wherein  pyrites  have  decomposed,  are 
gossans  of  a  more  or  less  similar  nature.  The  chief 
peculiarity  of  the  Mount  Morgan  Mine  is  the  extraordi- 
nary richness  of  the  ore  and  so  far  undeterminable  mag- 
nitude of  the  deposit,  also  the  somewhat  exceptionally 
pasty  nature  of  the  silica  residue,  before  noticed. 

As  an  illustration  of  how  minutely  divided  water-borne 
gold,  and  silica,  occur  in  the  waters  of  almost  all  mines, 
certain  experiments  which  were  carried  out  by  Mr.  J. 
Cosmo  Newbery,  chief  of  the  Technological  Museum, 


Losses.  39 

Melbourne,  throw  considerable  light  on  the  matter  :  Mr. 
Newbery  was  examining  mine  timbers  which  had  long 
been  saturated  by  mine  waters,  expecting  to  find  in  the 
fibres  of  the  timber,  gold,  which  had  been  precipitated  from 
solutions ;  its  soluble  condition  being  brought  about  by 
reactions  caused  by  the  decomposition  of  certain  salts 
held  by  mine  waters  as  before  explained.*  Some  large 
logs  of  undressed  close-grained  eucalyptus  timber,  which 
had  been  in  mine  waters  between  twelve  and  fourteen 
years,  were  experimented  upon,  the  outsides  of  these  were 
cut  away  and  perfectly  sound  pieces  were  obtained  ;  these 
were  dressed  quite  smooth  and  to  all  appearance  were 
as  ordinary  pieces  of  planed  timber.  They  were  then 
carefully  calcined  and  the  ash  examined ;  a  consider- 
able quantity  of  highly  minute  gold,  and  silica,  being 
found.  Microscopical  examination  of  these  showed  that 
both  gold  and  silica  were  in  rough  and  irregular  particles, 
quite  unlike  the  forms  they  would  have  assumed  had 
they  been  there  precipitated  from  solutions  ;  the  capillary 
attraction  of  the  wood  had  drawn  them  amongst  the 
fibres  together  with  the  water.  In  carrying  these  ex- 
periments further  Mr.  Newbery  endeavoured  to  obtain 
mine  waters  from  which  all  matter  held  in  suspension  had 
been  filtered,  so  as  to  test  for  metals  held  in  solution. 
For  this  purpose  he  passed  mine  waters  through  a  felt 
filter,  such  as  is  used  by  chemists  ;  even  after  this  he 
found  that  impalpably  minute  metallic  gold  had  passed 
with  the  water  through  the  pores  of  this  filter. 

At  Sandhurst,  Victoria,  the  customs  mills  crush  what 
are  usually  considered  free  milling  ores,  namely,  ordinary 
quartz  with  about  2  per  cent,  of  concentrates  ;  the  drain- 
age from  the  mills  run  into  a  creek.  The  tailings  at  the 

*  Properties,  pages  8-10. 


40  Losses. 

batteries  give,  by  assay,  an  average  return  of  about 
4  dwts.  to  the  ton.  As  lias  been  already  explained,  slimes, 
-are  the  fine  water-borne  portions  of  the  ore.  Some  of  the 
slimes  had  been  carried  by  the  water  for  miles  down  the 
creek,  and  concentrated  in  places  by  the  natural  ripples 
and  eddies  in  the  water ;  some  small  patches  were 
obtained  three  miles  below  the  batteries  which  returned 
by  assay  18  dwts.  of  gold  to  the  ton  of  concentrated 
slimes. 

Mr.  Edward  Dunn,  geologist  to  the  Cape  Government, 
brought  to  the  Melbourne  Technological  Museum  some 
gold  which  he  had  collected  in  South  Africa  from  the 
rock  called  "  banket."  The  gold  was  in  a  brown  dust, 
the  grains  of  which  were  so  fine  as  only  to  be  distinguish- 
able under  a  microscope  of  high  power.  When  thrown 
on  a  close-grained  white  paper  the  dust  discoloured  the 
paper  with  a  brown  stain  ;  this  examined  by  the  micro- 
scope proved  to  be  minute  gold  particles  caught  in  the 
fibres  of  the  paper.  A  small  quantity  of  this'  brown 
powder  put  in  a  test  tube  with  distilled  water  and  shaken 
up,  gave  a  distinct  purple  colour  to  the  water  with  trans- 
mitted light,  and  light  green  with  reflected  light ;  a 
considerable  time  elapsed  before  the  metal  deposited  and 
the  water  resumed  its  natural  colour. 

It  may  be  here  noted  that  any  illustrations  given  of 
the  finely  divided  condition  of  gold  are  only  in  proof  of 
its  common  occurrence  in  nature  in  such  a  form.  That 
metallic  gold  exists  in  a  still  more  infinitely  fine  condition 
is  indisputable,  and  may  be  easily  demonstrated  by 
solutions  permanently  coloured  by  fine  gold  which  give 
no  sediment  or  deposit. 

In     an     official    publication    of    the     United    States 


Losses.  41 

Government^  the  following  tests  by  Mr.  G.  McDougal, 
of  Grass  Valley,  California,  are  given  as  evidence  of  loss 
by  water-borne  gold ;  the  experiments  were  regarding 
two  mills  situated  in  that  locality. 

From  water  flowing  three-quarters  of  a  mile  below  mills  : 

Cents. 

1st  test  of  20  gallons  of  water  gave  gold  to  the  value  of  1.10 

2nd              „                  „                  „                  „                  „  2.13 

3rd               „                  „                  ,,                  „                  „  .95 

4th               ,,                  „                  „                  „                  ,,  .83 

5th               „                  „                  „                  „                  „  1.02 

6th               „                  ,,                  „                  „                  ,,  1.13 

^th  ,,  55  55  55  55  •  "  I 

8th  „  „  „  „  „  3.12 

9th  „  „  „  ;  „  „  1.07 

10th  „  55  „  „  5,  .63 

llth  „  „  „  „  „  1.01 

12th  ,,  „  »  „  „  -90 

Average     1.18 


It  was  estimated  that  576,000  gallons  of  this  muddy  water  flowed 
by  every  twenty-four  hours,  which,  according  to  these  testa,  contains 
339.84  dols.  Let  us  carry  this  calculation  a  little  further.  The  average 
amount  of  ore  worked  in  twenty-four  hours  was  given  at  58  tons  ;  this 
shows  that  5.85  dols.  float,  which  probably  is  20  per  cent,  of  the  yield. 
Let  us  carry  the  loss  a  little  further.  Suppose  that  the  two  mills  run 
250  days  in  each  year,  which  is  not  unreasonable,  and  we  have  a  yearly 
loss  of  float  gold  alone,  to  say  nothing  of  loss  by  imperfect  pulverisation 
and  general  wastage,  of  84,960  dols.  from  two  mills. 

From  the  same  source  as  the  above,  the  writings 
of  Mr.  Almarin  B.  Paul,  of  San  Francisco,  may  be 
quoted  : 

A  friend  of  mine,  having  somewhat  similar  ideas  to  my  own,  con 
eluded  to  test  the  question  of  float  gold  as  well  as  he  could  at  the  time 
and  embraced  the  opportunity  of  cleaning  up  the  slum  from  a  water 

*  "  Statistics  of  Mines  and  Mining  in  the  United  States  and  Terri- 
tories West  of  the  Rocky  Mountains,"  by  Rossi ter  W.  Raymond, 
United  States  Commissioner  of  Mining  Statistics. 


42  Losses. 

tank  for  supplying  the  battery,  where  the  water  was  used  over  and  over 
again  in  consequence  of  its  scarcity.  The  ores  were  worked  after  the 
usual  wet  methods  for  gold  ores.  The  water  and  pulp  were  first  passed 
through  a  sluice  to  a  tailing  bed,  190  ft.  The  tailings  being  deposited 
the  water  was  drawn  off  at  the  top,  flowing  into  a  well  where  it  was 
raised  and  passed  through  a  sluice  120  ft.  to  tank  at  battery.  This  is 
the  tank  cleaned  up.  The  residue  was  amalgamated  in  a  tub  quite 
rudely,  but  with  a  large  body  of  mercury  and  chemicals,  the  result  was 
33  dols.  in  silver  and  56  dols.  in  gold,  making  a  total  of  89  dols.  per  ton. 
It  will  be  observed  there  were  two  chances  for  the  metal  to  precipitate 
previous  to  reaching  this  tank  ;  first  in  the  tailing  reservoir  and  second 
in  the  well. 

In  another  part  of  the  same  article  Mr.  Paul  continues : 

Our  present  general  system  of  gold  mining  is  based  upon  the  idea 
that  gold  is  mainly  coarse,  while  examination  will  show  that  the  high 
percentage  is  in  atoms  finer  than  flour  itself.  In  my  experiments  gold 
has  been  taken  up  so  fine  that  in  distilled  water  it  would  not  precipitate 
in  less  than  from  five  to  ten  minutes.  Can  you  save  gold  of  this  kind 

by  running  it  down  stream  1 Gold  in  quartz,  of  gravity 

enough  to  resist  the  pressure  of  any  stream  of  water  is  the  exception, 
and  this  is  the  aggregation  of  the  finer  particles,  the  primary  simple 
condition,  in  my  opinion  being  flour  or  powder  of  gold.  It  is  the  flour 
of  gold  we  must  seek  to  obtain,  to  get  the  wealth  of  our  ores. 

Engineering,  of  the  26th  August,  1887,  referring  to 
Australian  practice,  says  : 

A  mining  manager  in  estimating  his  loss  of  gold,  generally  assays 
his  tailings  or  refuse  and  counts  the  loss  to  be  what  is  found  there, 
utterly  ignoring  the  large  percentage  which  is  swept  off  by  water  and 

disappears Water  that  has  flowed  through  the  battery 

and  deposited  tailings  in  various  receptacles,  until  apparently  quite 
clear  and  pure,  has  been  caught  in  a  dam  and  the  fine  sediment 
deposited  there  experimented  on  and  gold  of  an  extreme  fineness  found. 
One  writer  says  :  '  I  have  collected  some  of  this  gold,  which,  when 
shaken  in  a  bottle  of  distilled  water,  is  scarcely  visible;  it  colours  the 
water  a  light  purple  tint,  and  remains  suspended  for  a  long  time  ;  it 
seems  the  friction  of  the  gold  particles  with  the  water  is  powerful 
enough  to  nearly  neutralise  the  high  specific  gravity  of  the  gold.'  It 
will  be  seen  that  the  strong  current  flowing  through  the  battery  carries 
away  much  of  the  fine  gold,  over  the  tailing  heaps,  and  deposits  it  far 


Losses.  43 

and  wide  down  the  creek,  where  no  one  thinks  of  looking  for  it,  and 
even  if  they  did,  the  difficulty  of  collection  would  be  excessive. 

Though  not  dealing  with  alluvial  or  hydraulic  mining, 
it  is  of  interest  to  note  that  this  exceedingly  fine  gold 
occurs  in  alluvial  deposits,  and  that  some  of  it  is  capable 
of  being  saved  by  simple  mechanical  means. 

The  placer  mines  of  the  southern  counties  of  California  have  been 
regularly  worked  of  late  years,  except  where  there  was  an  insufficiency 
of  water.  In  the  winter  season,  when  there  is  an  abundance  of  water, 
the  miners  have  lately  learned  to  save  the  '  float  gold,'  a  nearly  im- 
palpable dust  which  floats  on  the  surface  of  the  water.  The  method 
adopted  is  quite  simple,  consisting  of  a  series  of  weirs  placed  across  the 
stream,  so  that  water  shall  flow  over  each  in  succession.  These  weirs 
are  constructed  of  piles  and  timber  with  coarse  gunny  cloth  covering 
the  upper  side.  In  rainy  seasons,  in  a  rich  gold-bearing  canon,  what 
extra  is  saved  by  the  weirs  is  estimated  at  from  10  dols.  to  30  dols.  per 
week,  according  to  the  richness  of  the  dirt  above  and  the  number  of 
weirs.  In  any  case  they  are  profitable,  as  their  cost  is  small.* 

In  Victoria,  Chinamen  make  a  good  living  by 
boiling  the  sludges  from  alluvial  mining,  in  iron  pots,  with 
mercury  and  water. 

A  2.  Fine  Gold  Particles  Encased  or  Attached  to  Pieces 
of  Rock  and  Carried  into  Tailings  or  Down  Stream. 
It  will  no  doubt  be  apparent  to  those  who  read  the 
notes  under  head  A  1,  that  no  such  thing  as  a  distinct 
line  exists  between  the  losses  under  the  former  head  and 
the  one  now  being  dealt  with  ;  the  present  is  simply  a 
coarser  condition  of  ore  residues,  one  more  generally 
known  and  more  easily  demonstrated  than  the  first. 
The  following  observations  and  experiments  being  more 
strictly  confined  to  what  are  commonly  known  as  tailings 
— a  coarser  condition  than  slime  residues — will  serve  as 
practical  illustrations  of  the  loss. 

*  "Production  of  Precious  Metals  in  the  United  States,"  1883,  by 
Walter  A.  Skidmore,  page  722. 


44  Losses. 

The  following  tests  were  carried  out  in  California  and 
are  recorded  by  Mr.  Paul  in  the  article  previously 
referred  to  under  head  A  1. 

Test  No.  1.  Average  yield  of  ore  in  mill  18.60  dols.  per  ton. 
Wastage  after  complete  washing  including  concentration ;  silver, 
3.14  dols.  ;  gold,  10.04  dols. ;  total,  13.18  dols.  per  ton. 

Test  No.  2.  Same  mill  tailings  350  ft.  from  mill.  Silver,  3.93  dols. ; 
gold,  5.02  dols.  •  total,  8.98  dols.  per  ton.  Showing  that  a  portion 
secreted  itself  in  passage  down  stream. 

Test  No.  3.  Average  yield  of  150  tons,  3.50  dols.  per  ton.  Assay 
of  tailings  (from  above  ore)  carefully  sampled.  Silver,  6. 28  dols. ; 
gold,  13.55  dols.  ;  total,  18.83  dols.  loss  per  ton.  Silver,  6.28  dols. ; 
gold,  8.79  dols. ;  total,  15.07  dols.  loss  per  ton. 

The  above  bad  results  were  occasioned  by  the  extreme  fineness  of 
the  gold,  and  the  above  does  show  the  full  wastage. 

In  another  portion  of  the  article  is  the  following  : 

I  made  a  test  of  50  Ib.  of  tailings  for  a  party  who  took  them  a  mile 
below  his  mill,  and  the  return  was  55  per  cent,  of  what  was  his  average 
working.  I  also  made  a  test  of  three-quarters  of  a  ton,  and  the  result 
showed  the  loss  in  the  mill  working  to  be  63  per  cent.  From  what 
attention  I  have  given  the  subject  in  actual  labour,  as  well  as  collecting 
all  the  data  attainable  in  others,  I  know  that  the  loss  as  a  whole  is 
fully  50  per  cent.,  and  in  the  majority  of  mills  all  of  60  per  cent,  of 

what  the  ore  contains One  step  in  advance   would  be,  taking 

more  care.  There  is  too  much  slashing  about  in  our  gold  mining  .... 
This  plan  of  seeing  how  much  can  be  pounded  up  and  rushed  through 

in  twenty-four  hours  is  a  false,  wasteful,  and  ruinous  system It 

is  too  universal  to  consider  that  it  is  only  necessary  to  rig  up  a  set  of 
stamps,  apply  the  power,  and  let  them  rip  away,  smashing  rocks  to 
wash  over  blankets  and  copper  plates  ;  and  all  is  done  with  a  stream  of 
water  to  wash  the  sand  off,  forgetting  that  it  is  equally  as  potent  to 
wash  off  the  smaller  particles  of  gold. 

A  3.   Clayey  ores  make  the  battery  water  very  muddy 
which  holds  mechanically  fine  gold  particles  in  sus- 
pension until  deposited  in  tailings  or  down  stream. 
When  an  ore  is  clayey  and  makes  muddy  water,  a  large 
percentage  of  the  gold  is  carried  away  in  suspension  by  the 
battery  water.     These  gold  particles  are  not  necessarily 


Losses.  45 

coated  by  mud,  attached  to,  or  contained  in  its  particles, 
but  are  kept  afloat  by  the  mechanical  action  of  the  mud. 
If  the  quantity  of  water  sent  through  the  battery 
is  reduced  so  as  to  give  the  gold  time  to  settle, 
the  mud  also  settles  and  covers  the  surfaces  of  the 
plates  and  prevents  amalgamation ;  an  increase  of  water 
frequently  washes  everything  away.  In  such  a  case  the 
usual  remedy  is  to  feed  into  the  battery,  together  with 
the  ore,  a  quantity  of  hard  material,  so  as  to  reduce  the 
proportion  of  clay  to  the  crushed  mass  passing  off  with 
the  water ;  this  means  a  highly  increased  cost  of 
treatment,  caused  by  obtaining,  handling,  and  crushing 
barren  and  worthless  material. 

Mr.  Deetken,  of  Grass  Valley,  California,  gives  as  the 
result  of  his  investigations,^  that 

Battery  sands  passing  through  a  No.  6  slot  screen  (25  mesh)  con- 
tain 19  per  cent,  of  slimes  which  remain  suspended  in  still  water  after 
three  minutes'  rest. 

To  obtain  even  this  result  the  ores  which  came  under 
Mr.  Deetken's  observation  must  have  been  especially 
good  settling  ores. 

A  4.  When  any  artificial  conditions  arise  whereby 
certain  substances  may  find  their  way  into  crushing 
mills  or  other  appliances,  practically  insuperable 
difficulties  may  be  occasioned;  similar  results  may 
arise  from  natural  films  coating  the  gold.  Any- 
thing which  creates  films  and  prevents  perfect 
contact  between  the  metals,  renders  the  gold  non- 
amalgamable,  therefore  all  but  the  heavier  particles 
will  be  swept  into  the  tailings  or  down  stream. 

In  cases  where  water  is  scarce,  much  of  it  is  frequently 

*  "  Statistics  of  Mines  and  Mining  in  the  States  and  Territories  West 
of  Rocky  Mountains." 


46  Losses. 

obtained  from  the  mine  pumpings,  which  are  always  more 
or  less  saline,  and  it  is  used  over  and  over  again  to  carry 
.  the  ore  through  the  battery;  it  flows  over  tailing  heaps  and 
into  pits  to  deposit  slimes,  from  whence  it  is  pumped 
back  to  the  battery,  therefore  it  is  continually  coming  into 
contact  with  crushed  ore  which  has  been  exposed  to 
atmospheric  action.  Very  many  ores  contain  one 
or  two  per  cent,  of  sulphurets,  a  quantity  not  sufficient 
to  remove  them  from  the  class  of  free  milling  ores  ;  these 
crushed  sulphurets  rapidly  decompose  when  exposed  to 
the  atmosphere,  and  sulphuric  acid  is  produced,  which  is 
dissolved  by  the  water ;  the  more  often  the  water  per- 
colates through  the  heaps  of  crushed  ore,  the  more 
heavily  does  it  become  charged  with  sulphuric  acid  and 
acid  sulphates.  When  this  acidulated  water  is  used  in 
a  battery  many  complicated  reactions  may  take  place. 
As  an  illustration  the  case  of  a  ship's  propeller 
may  be  cited.  It  is  well  known  that  when  a  gun- 
metal  propeller  is  fixed  in  an  iron  ship,  without 
being  properly  insulated,  and  run  in  salt  water, 
a  galvanic  action  is  set  up  between  the  ship  and  the  pro- 
peller, so  that  the  stern-post  and  ship's  bottom  rapidly 
corrode  and  waste  away.  In  like  manner,  if  an  iron 
stamper  battery  with  copper  plates  be  run  empty,  and 
at  the  same  time  acidulated  waters  be  passed  through, 
it  is  at  once  converted  into  a  galvanic  battery ;  if,  while 
in  this  condition  a  number  of  other  substances  contained 
in  the  ore  are  introduced,  a  fresh  set  of  actions  are  set 
up;  these  produce  re-actions  and  so  on,  until  the  chemical 
changes  taking  place  inside  the  battery  boxes  become 
very  highly  complex  and  to  the  average  miner  absolutely 
inexplicable;  though  a  worker  may  understand  thoroughly 
all  the  individual  actions,  there  are  few  who  can  follow 


Losses.  47 

these  endless  combinations  and  their  detrimental  effect 
in  rendering  gold  non-amalgamable.  It  is  from  the 
corrosive  action  set  up  in  the  manner  explained,  together 
with  the  peculiar  molecular  change  produced  by  acid 
saline  waters — to  be  noted  hereafter — that  gratings  so 
frequently  burst,  flood  the  plates,  and  cause  all  kinds  of 
trouble  to  the  millman. 

The  formation  of  films,  and  other  causes  which  pre- 
vent amalgamation,  may  be  accounted  for  by  the  presence 
in  the  stamper  battery  or  other  appliance,  of  certain 
soapy  varieties  of  powdered  hydrated  silicates  of 
magnesia,  or  alumina,  grease,  urine,  decomposing  animal 
or  vegetable  matter  contained  in  impure  water,  or  water 
impregnated  with  sulphuretted  hydrogen,  or  containing 
certain  soluble  metallic  salts.  Excessive  hammering  from 
stamp  action,  air  globules  adhering  to  minute  gold 
particles,  and  other  causes,  renders  gold  non-amalga- 
mable, but  the  effect  of  some  of  the  substances  noted 
are  most  felt  in  amalgamators. 

Mr.  William  Skey,  the  analyst  to  the  Geological  Sur- 
vey of  New  Zealand,  when  writing  on  the  reported  loss 
of  gold  on  the  Thames  field,  gives  the  following  as  the 
result  of  his  researches  : 

That  numerous  samples  of  bright  clean  gold  of  all  degrees  of 
fineness,  refuse  to  amalgamate  on  any  part  of  their  natural  surfaces 
though  taken  direct  from  the  reef  and  untouched  by  hand. 

That  on  such  surfaces  sulphur  is  always  present. 

That  native  gold,  or  gold  in  a  pure  state,  readily  absorbs  sulphur 
from  moist  sulphuretted  hydrogen  or  sulphide  of  ammonium.  .  .  . 

That  surfaces  so  affected  refuse  to  amalgamate  though  no  apparent 
change  can  be  observed  in  their  aspect. 

The  action  of  sulphuretted  hydrogen  upon  gold  in  rendering  it  non- 
amalgamable  when  placed  in  contact  with  mercury  was  demonstrated 
with  striking  effect  by  the  author.  From  these  results  the  author  has 
been  led  to  suppose  that  a  large  area  of  the  natural  surfaces  of  native 


48  Losses. 

gold  is  covered  with  a  thin  film  of  an  auriferous  sulphide,  and  that  the 
greater  part  of  the  gold  which  escapes  amalgamation  at  the  battery  is 
represented  by  that  portion  of  this  sulphurised  gold  which  has  remained 
unabraded  during  the  process  of  milling  or  extraction  from  the  reef  ; 
the  state  of  the  gold,  rather  than  that  of  the  mercury,  therefore,  being 
the  greatest  impediment  to  thorough  amalgamation. 

That  this  absorption  is  altogether  of  a  chemical  nature. 

In  ores  where  acidulated  water  is  not  in  itself  sufficient 
to  produce  sulphuretted  hydrogen,  the  galvanic  action 
before  mentioned  will,  when  set  up,  at  once  bring  about 
the  production  of  the  gas  in  places  where  it  can  most 
readily  exert  its  influence  on  the  gold. 

Referring  to  the  causes  preventing  gold  amalgamating,. 
Professor  Egleston,  Ph.  X).,  School  of  Mines,  New  York 
City,  writes  as  follows  :* 

In  order  to  ascertain  the  causes  which  prevent  the  amalgamation  of 
gold,  I  undertook  to  reproduce  artificially  the  conditions  which  were 
supposed  to  prevent  it.  These  I  found  to  be  mechanical  and  chemical. 
I  found  that  if  a  piece  of  soft  gold,  which  could  be  easily  bent  and 
amalgamated  readily,  was  hammered  on  a  perfectly  bright  anvil 
with  a  bright  hammer,  given  several  rapid  blows  until  the  gold  had 
become  hard,  and  had  acquired  a  certain  amount  of  elasticity,  it 
would  remain  in  juxtaposition  with  mercury  for  a  very  long  time 
without  being  affected  by  it.  This  hammering  increases  the  density 
of  the  metal  and  closes  the  pores,  so  that  I  have  recently  had  a  piece 
of  gold,  which  was  put  into  this  condition  by  hammering,  remain 
nearly  two  weeks  floating  on  the  mercury  without  being  attacked.  If 
gold  in  this  condition  is  heated  and  cooled  slowly,  it  again  amalgamates 
rapidly.  If,  however,  it  is  cooled  rapidly  by  plunging  it  suddenly  into 
very  cold  water,  the  amalgamation  takes  place  very  slowly.  The  metal, 
after  being  repeatedly  rapidly  cooled  and  heated,  amalgamates  more 
readily  than  if  it  has  only  been  treated  onoe. 

....  The  effects  of  grease  are  well  known,  and  the  greatest  care 
is  taken  in  most  mills  to  keep  the  '  quick't  bright,  either  by  rubbing  or 
by  the  addition  of  chemicals,  to  such  an  exent  in  some  cases,  that  the 
chemical  themselves,  used  in  excess,  are  often  a  cause  of  the  very  thing 

*  Transactions  American  Institute  of  Mining  Engineers,  vol.  ix.,, 
page  633. 

f  Mercury  and  amalgam. 


Losses.  49 

they  are  intended  to  prevent.  All  these  causes,  the  hammering,  the 
effect  of  sulphuretted  waters,  and  also  the  effect  of  grease,  occur  in 
every  mill,  and  probably  have  something  to  do  with  the  losses  of  gold 
which  take  place  there. 

It  will  thus  be  seen  that  the  stamp  mill  is  not  a  rationally  designed 
machine.  The  action  of  the  pounding  is  likely  to  put  some  of  the  gold 
into  such  a  condition  that  mercury  will  not  touch  it,  and  to  flour  the 
gold  as  well  as  the  quicksilver.  There  is,  besides,  in  the  mill  every 
probability  of  the  introduction  of  grease  or  greasy  substances,  like  the 
powdered  hydrated  silicates  of  magnesia  and  of  alumina,  which  not 
only  froth  but  coat  the  gold  with  a  slime  which  prevents  the  action  of 
the  mercury.  If  the  water  used  in  the  mill  is  not  pure,  there  is  a  fur- 
ther likelihood  of  the  introduction  of  sulphuretted  hydrogen,  and  of 
other  soluble  sulphides,  which  act  superficially  on  small  particles  of 
gold  and  prevent  the  action  of  the  mercury. 

A  5.  Though  gold  be  in  a  perfect  condition  for  amal- 
gamation, impure  mercury  will  not  act ;  in  such  a  case 
all  but  the  heavier  gold  particles  would  be  washed 
into  tailings  or  down  stream. 

This  is  one  of  the  points  brought  daily  under  the  notice 
of  millmen  in  any  reduction  works.  Careful  workers 
will  guard  against  the  introduction  of  grease  and  many 
other  substances  which  act  deleteriously  on  mercury  ; 
but  there  are  cases  where  the  mercury  becoming  foul 
in  boxes,  in  ripples,  and  on  the  plates,  defies  all  like  pre- 
cautions. One  of  the  principal  causes,  especially  where 
the  trouble  is  found  with  amalgamated  plates,  no  doubt 
results  from  the  action  of  saline  and  acidulated  waters, 
already  explained.  In  any  case,  if  thoroughly  investi- 
gated, the  objectionable  influence  may  be  traced,  provided 
the  worker  has  sufficient  chemical  knowledge,  and  in  such 
a  case  a  remedy  can  doubtless  be  applied.  This  cause  of 
loss  and  those  under  head  A  4  are  so  closely  allied  that 
it  is  almost  impossible  to  say  where  one  ends  and  the 
other  begins. 


50  Losses. 

A  6.  Though  gold  and  mercury  be  in  a  perfect  condi- 
tion for  amalgamation,  and  have  amalgamated^ 
excessive  stamping  in  batteries,  agitation,  or  grind- 
ing in  machinery,  and  other  causes,  bring  about 
granulation  of  the  amalgam  and  leave  it  in  a  con- 
dition to  be  readily  carried  off  by  water,  either  into 
tailings  or  down  stream. 

The  action  of  a  falling  stamp,  or  a  grinding-pan,  breaks 
mercury  up  into  small  particles  which  assume  a  globular 
form.  If  perfectly  clean  mercury  were  broken  up  by  a 
perfectly  clean  practically  infriable  machine,  doubtless, 
no  amount  of  grinding  would  prevent  the  particles 
reuniting,  unless  air  globules  or  finely  powdered  foreign 
substances  were  present  which  could  coat  the  particles. 
In  stamp  mills  and  grinding  pans  the  wear  of  metal  is 
very  heavy,  it  is  continually  coming  away  in  very  minute 
particles ;  excessive  stamping  or  grinding  also  produces 
minute  ore  particles.  The  shining  surfaces  of  the  mer- 
cury rapidly  become  coated  therewith,  and  films  are  con- 
sequently created  which  prevent  the  globules  reuniting; 
the  longer  any  material  and  mercury  are  together  subject 
to  the  action  of  machinery,  the  more  likelihood  there  is 
of  loss  accruing.  When  treating  a  free  milling  ore  in  a 
well-managed  and  regulated  plant,  if  the  loss  of  amalgam 
is  great,  close  investigation  will  frequently  reveal  a 
special  cause,  such  as  the  action  of  some  heavy  mineral 
contained  in  the  ore;  the  presence  of  heavy  spar,  scoro- 
dite,  &c.,  or  like  substance  may  not  be  noticed,  owing  to 
similarity  in  colour  to  the  ore,  until,  on  the  stripping  of 
the  plates,  the  manager  looks  for  the  cause  of  the  loss. 

Rossiter  W.  Raymond,  when  United  States  Commis- 
sioner of  Mining  Statistics,  wrote  as  follows  :* 
*  Raymond's  reports,  1870. 


Losses.  51 

Floured  or  granulated  quicksilver,  or  fine  particles  of  gold,  have  in 
common  with  some  other  polished  metals  the  property  of  condensing  on 
their  surface  films  of  air  which  decrease  the  specific  gravity  of  particle. 
As  the  amount  of  air,  hence  the  amount  of  decrease  in  specific  is  pro- 
portional to  the  surface  exposed,  and  its  ratio  to  the  mass  of  the  par- 
ticle ;  and  as  the  smallest  particles  expose  always  the  largest  propor- 
tional surfaces  (the  cube  roots  of  the  volumes  being  as  the  square  roots 
of  the  surfaces),  it  follows  that  very  fine  particles  will  acquire  a  density 
less  than  of  water,  and  will  in  fact  float  upon  it.  Many  more  will  be 
rendered  so  light  as  to  settle  very  slowly. 

Mr.  Charles  G.  Yale,  writing  in  the  official  publication 
of  the  United  States  Government  "  Precious  Metals  in 
the  United  States/'  states  :  * 

Swinging  plates  for  float  gold  are  now  in  use  in  many  places  in 
California,  and  in  other  gold  regions  on  the  Pacific  coast.  They  are 
all  adapted  for  use  in  the  sluice  below  the  battery  of  a  quartz  mill  or 
in  sluices  in  any  position  where  there  is  not  too  great  a  flow  of  water 
or  material. 

The  swinging  plate  consists  of  a  curved  strip  of  silver-plated 
amalgamated  plate,  about  3  in.  deep,  and  the  width  of  the  sluice  or 
flume  in  which  it  is  to  be  used.  It  is  swung  on  eyes,  through  which 
passes  a  wire  rod  resting  on  the  edges  of  the  sluice.  The  plate  thus 
hangs  transversely  to  the  current,  with  its  concave  face  up  stream,  the 
plate  being  half  submerged.  The  movement  of  the  water  will  keep  the 
plate  swinging.  The  floating  particles  of  gold  cannot  escape  touching 
the  plate,  and  are  caught  on  the  quicksilver  surface. 

It  is  found  in  practice  that  across  the  sluice,  immediately  under 
each  swinging  plate,  is  formed  a  line  of  amalgam,  which  has  dropped 
from  the  plate  as  it  accumulated.  The  gold  which  is  caught  on  the 
plate  is  thus  saved.  These  plates  are  hung  in  sluices  a  few  feet  apart. 

Very  wide  ones  have  been  made  for  the  sluices  of  hydraulic  mines. 
The  plates  cost  so  very  little  and  are  so  effective  that  they  have  come 
into  extensive  use.  They  are  silver-plated,  the  same  as  the  ordinary 
plates  in  use  in  quartz  mills. 

Although  the  foregoing  is  a  most  practical  proof  of 
the  existence  of  floating  gold  and  amalgam,  yet,  as  a 
matter  of  fact,  it  is  only  likely  to  save  a  very  small  pro- 
portion of  the  total  quantity  carried  away,  and  most  of 

*  1881. 


52  Losses. 

the  floating  gold  and  amalgam  do  escape  contact  with 
the  amalgamated  plate.  The  action  of  water  when 
flowing  under  any  obstruction  is  so  well  known  that  it 
need  not  be  entered  upon,  save  to  point  out,  that  a 
cushion  of  comparatively  still  water  is  always  imposed 
between  the  flowing  current  and  the  obstruction  and  it 
is  against  the  outer  portions  of  this  cushion  that  the 
large  proportion  of  floating  substances  would  strike. 

In  concluding  these  notes  and  references  to  the  great 
losses  occasioned  by  many  causes  in  the  so-called  "  free 
milling  ores,"  the  following  from  the  pen  of  Mr.  J.  R. 
Hardenberg*  should  be -learned  as  an  article  of  faith  by 
all  gold  miners,  and  every  one,  speculator  or  otherwise, 
who  has  any  connection  with  the  industry. 

....  The  simple  truth  is  that  since  the  beginning  of  quartz 
mining  in  California,  those  who  have  engaged  in  it  have  been  misled 
or  have  misled  themselves  by  the  fallacy  involVed  in  miners  ignis 
fatuuS)  covered  by  the  hackneyed  experience  of  the  milling  ores.  As  a 
rule  the  whole  of  the  quartz  mining  in  California  until  a  very  recent 
period  has  been  carried  on  upon  the  basis  of  the  "  f ree  milling"  pro- 
position, meaning  mining,  crushing,  pulverising,  and  extracting  gold 
by  the  amalgamating  process,  and  regardless  of  the  fact  that  the  per- 
centage of  gold  contained  in  pulp,  capable  of  being  caught  and  retained 
by  the  agency  of  quicksilver  in  whatever  form  it  may  have  been  used, 
has  been  but  a  fraction  of  the  assay  value  of  the  whole  mass,  while 
larger  proportions  have  as  regularly  gone  to  waste  as  the  water  has 
flowed  from  the  batteries  in  which  the  ore  has  been  treated.  The 
result  achieved,  therefore,  from  the  working  of  these  ores  has  been  but 
a  small  part  of  the  assay  value,  which  has,  in  the  main,  only  served  as 
a  "  will-o'-the-wisp  "  to  lead  capital  and  human  energy  to  merciless 
wreck  and  ruin.  In  spite  of  all  this,  in  spite  of  years  of  costly  and 
destructive  experience,  men  have  persistently  continued  to  engage  in 
mining  enterprises  to  be  carried  on  in  the  old  manner,  and  to  result  in 
the  continued  accumulation  of  abandoned  monuments  of  lost  capital 
and  stranded  human  hopes. 

*  Writing  on   California,   in  the  official  publication  of  the  United 
States  Government  "  Precious  Metals  in  the  United  States,  1882." 


Losses.  53 

The  free  milling  manner,  while  it  has,  despite  the  fallacy  which  it 
involves,  helped  largely  to  swell  the  yearly  aggregate  of  California's, 
gold  product,  by  reason  of  its  inadequacy  and  utter  inefficiency  has 
visibly  retarded  her  mineral  development,  and  kept  her  yearly  gold 
product  far,  very  far,  below  the  figure  that  her  natural  resources  and 
the  natural  energy  of  her  people  call  for.  It  has  taken  long  years  and 
the  sacrifice  of  many  hundreds  of  thousands  of  dollars  to  clearly 
demonstrate  this  fallacy,  but  miners  and  mining  men  have  pursued  the 
phantom  with  a  determination  bordering  on  self-destruction  rather 
than  to  abandon  the  free  milling  madness  and  the  solace  afforded  for 
disasters  by  the  rebellious  ore  theory.  The  simple  truth  is  that  the 
wealth,  the  next  to  inexhaustible  gold  wealth  of  California,  lies  in  the 
so-called  rebellious  ores  themselves,  which  are  in  no  sense  rebellious 
other  than  that  the  gold  which  they  contain  cannot  be  extracted  by 
any  known  free-milling  amalgamating  process,  any  more  than  roast 
beef  can  be  converted  into  chicken  soup,  or  flesh  into  fish. 

....  Enough  to  say  that  all  authorities,  and  they  might  be 
quoted  to  endless  length,  agree  that  such  losses  constantly  occur  under 
the  system  of  gold  mining  which  has  heretofore  prevailed ;  and  to  add 
as  the  necessary  corollary,  that  this  system  has  been,  almost  exclusively, 
the  stamp  mill  and  amalgamation,  in  one  form  or  another,  or,  to  return 
to  our  tough  matter,  "free  milling." 

B.  LOSS  OF  GOLD  IN  REFRACTORY  ORES. 

The  general  methods  adopted  for  treating  "  refractory 
ores  "  have  followed  so  closely  the  ordinary  procedure 
for  working  "free-milling  ores"  that  very  many  of  the 
causes  of  loss  will  be  identical  with  those  previously 
enumerated. 

B  1.  Fine  gold  held  in  suspension  by  water  and 
carried  down  stream. 

The  causes  bringing  about  this  loss  are  almost  identical 
with  those  mentioned  under  head  A 1 ,  but  with  ores 
called  '''refractory"  or  "rebellious"  the  difficulty,  inmost 
cases,  is  likely  to  become  more  acute. 

In  all  metallurgical  operations  where  ores  are  crushed 


54  Losses. 

so  as  to  liberate  the  mineral  from  its  enveloping  gangue, 
and  these  crushings  subsequently  treated  by  a  stream  of 
water,  the  formation  of  slimes — so  easily  carried  away — 
is  the  greatest  source  of  loss.  As  a  rule  the  portions  of 
the  ore  containing  the  largest  quantity  of  mineral  are  by 
far  the  most  brittle.  As  in  most  crushing  operations  the 
whole  body  of  ore  is  reduced  until  it  is  sufficiently  small 
to  pass  through  a  particular  screen.  The  operation  neces- 
sary to  reduce  the  gangue  to  this  condition  must  be 
continued  long  after  the  mineral  portions  are  of  the 
required  size,  and  as  all  together  are  subject  to  the 
action  of  machinery,  the  reduction  of  a  large  proportion 
of  mineral  to  an  impalpable  powder  follows  as  a  natural 
consequence  the  process  of  reducing  its  hard  enveloping 
matrix  to  screen  sizes.  In  a  great  many  cases  these 
minerals  are  distributed  through  the  matrix  in  individual 
pieces  sufficiently  small  to  pass  through  the  screens  pro- 
vided for  the  purpose  of  regulating  this  size.  In  such  a 
case  they  simply  require  liberating,  yet  the  operation  of 
doing  so  invariably  results  in  bringing  a  large  proportion 
of  them  to  such  a  degree  of  fineness  that  they  become  a 
positive  impediment  to  metallurgical  operations  as  well 
as  a  source  of  great  loss  of  metal.  With  ores  holding 
metallic  sulphides,  &c.,  in  large  lumps,  the  result  is  the 
same  owing  to  the  crystalline  and  friable  structure  of  such 
metallic  bodies. 

As  a  simple  demonstration  of  the  foregoing:  take  an 
ore  containing  metallic  sulphides,  rub  it  with  the  fingers 
or  a  piece  of  white  cloth  or  paper,  and  examine  with  a 
microscope  the  resulting  stain,  it  will  be  found  to  consist  of 
a  number  of  minute  metal  lie  grains;  where  decomposition  is 
going  on  the  result  is  more  plainly  seen.  Another  method, 
and  one  which  follows  the  principles  generally  adopted  in 


Losses.  55 

treating  ores,  is  :  Put  a  piece  of  mineralised  ore  into  an 
ordinary  mortar  and  give  it  a  few  blows  and  turns  with 
a  pestle,  the  result  will  be  a  few  lumps  of  ore  and  gangue, 
a  proportion  of  sand-like  sizes,  and  also  a  quantity  of  fine 
dust.  Throw  half  of  this  into  a  long  glass  test  tube,  a  large 
proportion  of  the  stones  and  metal  will  sink  to  the  bottom 
at  once,  the  sand  will  settle  slowly,  the  dust  very  slowly, 
and  in  most  cases  the  water  will  be  discoloured ;  this  dis- 
coloration is  caused  by  particles  of  mineral  too  minute 
to  be  discerned  by  the  unaided  eye,  which  are  held  in 
suspension  by  water.  Then  treat  the  other  half  in  the 
mortar  until  reduced  to  sizes  common  in  the  treatment  of 
gold  ores,  say  ^th  of  an  inch  in  diameter — 40-mesh 
screen — then  throw  these  crushings  into  another  test 
tube,  and  observe  the  result ;  most  frequently  the  water 
will  be  highly  discoloured  and  remain  so  for  days, 
and  the  crushings  will  find  their  way  to  the  bottom 
according  to  their  relative  weights  which,  broadly  speak- 
ing, is  more  governed  by  size  than  density.  If  this 
discoloured  water  be  poured  off  and  allowed  time  to 
settle,  the  sediment  would  give  a  far  higher  return  ot 
metal  than  the  coarser  portions  of  the  ore  which  fall  to 
the  bottom  quickly. 

Such  sediments  compose  the  "  slimes  "  which  unfortu- 
nately in  the  majority  of  mills  are  considered  as  unat- 
tractive, objectionable,  and  valueless,  as  their  name 
would  imply,  and  are  accordingly  got  rid  of  with  the 
greatest  possible  celerity. 

The  following  extracts  from  a  paper  read  by  Mr. 
George  Latta  before  the  Royal  Society  of  New  South 
Wales  throw  considerable  light  on  the  condition  of  gold 
when  associated  with  refractory  ores. 

In  reference  to   the   condition  of  gold  in  pyrites  it  has  come  to  be 


56  Losses. 

pretty  generally  admitted  that  '  nearly,  if  not  quite,  all  the  gold  exists 
in  the  metallic  state.' 

This  quite  agrees  with  the  results  of  some  experiments  carried  out 
by  myself  in  conjunction  with  Mr.  Daintree,  late  of  the  Victorian 
geological  staff.  Our  researches  ended  in  our  obtaining  but  the  barest 
possible  evidence  of  gold  existing  in  a  mineralised  state  in  pyrites.  As 
a  matter  bearing  somewhat  in  support  of  this  result,  and  whilst  engaged 
in  these  investigations,  I  had  the  good  fortune  to  come  across  some 
good  specimens  of  cubical  pyrites,  which  upon  examination  with  a 
pocket  lens,  seemed  to  indicate  the  presence  of  gold ;  upon  transferring 
them  to  a  good  microscope,  gold  was  distinctly  seen  upon  the  planes  of 
cleavage,  and  upon  dissecting  the  crystals  every  cleavage  face  was 
found  distinctly  gilded.  Now  from  the  fact  that  the  presence  of  gold 
could  only  be  determined  by  the  aid  of  a  good  microscope,  and  that 
only  as  a  fine  gilding,  some  notion  may  be  formed  of  the  excessively 
fine  state  of  its  division,  and  how  unsatisfactory  would  be  the  task  of 
separating  such  liberated  films  from  water  in  motion. 

Guided  by  these  considerations  it  became  evident  that  any  attempt 
to  mechanically  separate  gold  from  pyrite — unless  aided  by  the  previous 
decomposition  of  its  enveloping  sulphides — must  prove  ineffectual  from 
the  impossibility  of  reducing  it  to  its  ultimate  atoms,  for  so  long  as  a 
cluster  of  sulphide  atoms  remain  unbroken,  they  might  reasonably  be 
imagined  to  contain  those  of  gold.  Again  it  was  equally  clear  that 
when  such  gold  was  liberated  from  its  envelope,  water  concentration 
alone  was  inapplicable.  To  test  the  correctness  of  these  conclusions, 
each  of  them  was  made  a  subject  of  rigid  examination,  over  an  extended 
scale,  before  receiving  them  as  fundamental  truths  to  guide  us  in  deter- 
mining the  best  methods  suitable  to  our  requirements.  Two  parcels  of 
pyrites,  20  tons  each — one  roasted,  the  other  unroasted — were  ground, 
in  one  of  the  best  arrastras  known,  with  mercury  ;  a  constant  stream 
of  water  flowing  through  to  carry  off  the  finely -ground  sand,  which  was 
then  carried  through  mercury  boxes  and  over  blankets.  Each  parcel 
receives  the  same  amount  of  grinding  and  treatment  in  every  detail ; 
the  result  is  as  follows  : 

20  tons  raw  sand  containing  3  oz.  6  dwts.  per  ton. 

Gold  obtained     .          .         .         .          .          .29.21  per  cent. 

„     left  in  tailings 42.84         ,, 

„     carried  off  in  water     ....     27.95         „ 

20  tons  roasted  sand  containing  1  oz.  7  dwts.  10  grs.  per  ton. 

Gold  obtained     .          .          .          .          .          .51.75  per  cent. 

„     left  in  tailings 27.21          „ 

„     carried  off  by  water     ....     21.22         „ 


Losses.  57 

Here  it  will  be  observed  that  with  the  raw  sand  only  a  small  portion 
of  the  gold  was  obtained,  a  very  much  larger  was  left  in  the  tailings 
although  finely  ground,  and  a  large  proportion  was  carried  off  by  the 
water  as  slime.  With  the  roasted  mineral  more  than  half  the  gold  was 
obtained  ;  the  tailings  were  very  much  poorer  than  those  from  the  raw 
sand,  but  still  very  rich,  and  a  large  quantity  was  carried  off  by  water. 

Mr.  Latta  then  describes  the  various  methods  sug- 
gested to  destroy  the  pyrite  envelope  ;  eventually  it  was 
decided  to  roast  all  the  pyrites  (a  parcel  of  294  tons) 
and  grind  in  a  Chilian  mill  for  about  three-quarters 
of  an  hour  equal  weights  of  damped  ore  and  mercury 
— practically  the  ancient  amalgamating  method  of 
the  Mexicans  and  South  Americans,  used  chiefly 
in  treating  silver  ores.  After  the  ore  and  mercury 
were  thoroughly  ground  and  intermixed,  water  was 
introduced  and  the  mill  set  revolving  slowly  until 
puddle  was  formed.  A  continuous  stream  of  water  was 
then  run  in  while  the  mill  revolved  until  all  the  tailings 
sands  were  carried  off.  These  were  twice  concentrated 
in  "  buddies "  to  save  the  fine  amalgam  lost  from  the 
Chilian  mill ;  efforts  were  made  to  curtail  the  amount  of 
grinding,  for  the  purpose  of  reducing  the  loss  in  mercury, 
but  whenever  grinding  was  lessened  a  heavy  loss  of  gold 
resulted.  Mercury  to  the  extent  of  1  Ib.  13  oz.  was  lost 
in  treating  one  ton  of  ore,  or  a  total  of  533  Ib.,  worth 
about  90/.  The  cost  of  treatment,  not  including 
interest  on  capital,  cost  and  wear  and  tear  of  machinery, 
was  equal  to  2l.  2s.  4d.  per  ton,  a  total  of  622Z.  6s.  The 
gold  saved  by  the  process  amounted  to  95.19  of  assay 
values,  but  for  individual  lots  as  high  returns  as  98  per 
cent,  were  obtained.  The  return  of  gold  is  given  at  4^  oz. 
per  ton  (value  not  stated),  therefore  the  total  quantity 
lost  was  worth  about  235/.  Satisfactory  as  the  percentage 
saved  appears  to  be,  more  correct  modern  methods  would 


58  Losses. 

have  resulted  in  the  saving  of  about  530/.  in  treating  this 
small  parcel  of  294  tons;  the  sum  would  be  considerably 
increased  if  the  very  heavy  cost  of  wear  and  tear  of 
machinery  had  been  included. 

At  the  Walhalla  Mine  in  Victoria,  Mr.  Henry  Rosales 
has  worked  for  many  years  in  a  somewhat  similar  fashion, 
and  has  obtained  almost  the  assay  values  of  his  concen- 
trates. Unroasted  concentrates  are  ground  and  amalga- 
mated in  Hungarian  mills  fixed  in  series,  and  by  this 
means  better  results  are  obtained  than  by  the  more  ordi- 
nary methods  of  calcination  and  amalgamation.  A  simple 
statement  to  this  effect  may  be  misleading,  but  without 
a  more  intimate  knowledge  of  the  details  of  Mr.  Resales' 
workings  it  is  impossible  to  say  whether  a  loss  was  not 
brought  about  by  the  manner  in  which  the  roasting 
operations  were  conducted.  At  all  events,  it  is  well 
known  that  improper  roasting  or  hurrying  the  process 
always  results  in  very  great  losses  of  gold.  In  the  par- 
ticular case  under  notice  there  were  unusual  conditions 
present  to  bring  about  satisfactory  results  :  a  surplus  of 
battery  engine  power,  utilised  in  driving  the  Hungarian 
mills  ;  the  quantity  of  concentrates  not  exceeding  ten 
tons  monthly ;  the  whole  month  available  for  their  treat- 
ment ;  and  the  individual  care  and  attention  devoted, 
unusual  to  a  marked  degree.  Although  the  foregoing 
method  was  so  adaptable  at  the  Walhalla  Mine,  when 
tried  on  the  concentrates  of  the  adjoining  mine — the  Long 
Tunnel — it  entirely  failed  to  produce  satisfactory  results. 

In  reference  to  the  question  of  gold-bearing  pyritous 
ores,  Mr.  Melville  Atwood,  in  a  paper  prepared  for  the 
State  Mining  Bureau  of  California,*  referring  to  Mr. 
Latta's  researches,  writes  as  follows  : 

*  "Precious  Metals  in  the  United  States,"  1881. 


Losses.  59 

It  is  now  generally  admitted  by  metallurgists  of  any  note  that  gold 
in  pyrites  exists  in  a  metallic  state.  It  is  with  no  little  pleasure  I  am 
enabled  to  practically  corroborate  the  statements  of  Mr.  Latta  on  the 
subject,  having  produced  for  your  inspection  a  number  of  crystals  and 
fragments  of  crystals  of  auriferous  pyrites  obtained  from  different  parts 
of  this  state.  They  are  mounted  on  glass  slides  for  microscopic  exami- 
nation, as  with  a  common  lens  the  presence  of  gold  can  hardly  be 
detected,  but  with  a  good  microscope,  using  a  1  in.  or  ^  in.  objective,  it 
will  be  found  that  the  faces  of  some  of  the  crystals  are,  in  places,  most 
finely  and  beautifully  gilded,  and  that  here  and  there  are  seen  little 
specks  or  drops  of  gold,  partially  imbedded  in  the  pyrite. 

The  mill-man  looking  at  these  specimens  will  not  be  surprised  at  the 
loss  sustained  in  the  wet  stamping  of  auriferous  pyrites. 

B  2.     Fine  gold  attached  to  pieces  of  rock,  or  encased 
in  pieces  of  base  minerals,  and  carried  into  tailings. 

The  notes  under  head  B 1  practically  comprise  the  answer 
to  this  inquiry,  but  the  following  experiment  gives 
answer  to  a  problem  which  often  appears  inexplicable 
to  miners  and  others  working  with  auriferous  pyritous 
ores. 

It  has  many  a  time  been  noticed  that  certain  gold- 
bearing  pyrites,  when  roasted,  then  crushed  and  subjected 
to  a  stream  of  water,  or  washing,  leave  a  residue  of  fine 
gold  particles  behind  when  all  other  crushed  matter  is 
washed  off,  and  that  if  a  portion  of  this  same  pyrites  be 
crushed,  without  roasting,  no  gold  of  any  description  can 
be  seen  after  similar  washing.  In  order  to  throw  some 
light  on  the  phenomenon  the  following  tests  were  insti- 
tuted : 

In  the  Walhalla  district,  Victoria,  certain  pyrites  in 
the  bed  of  a  creek  gave  by  assay  the  return  of  150  oz.  of 
gold  to  a  ton.  When  these  pyrites  were  crushed  no  gold 
was  visible  to  the  unaided  eye,  though  after  roasting, 
they  were  found  to  be  full  of  small  gold  specks. 
Several  cubes  of  pyrites  were  obtained,  which  had  passed 


60  Losses. 

through  a  30-mesh  screen  ;  these  were  carefully  examined 
and  no  trace  of  gold  was  discernible,  even  when  using  a 
powerful  microscope.  Several  cubes  were  placed  on  the 
tablet  of  a  microscope,  and  a  1-inch  objective  used  ;  they 
were  then  subjected  to  a  blowpipe  oxidising  flame,  and  the 
process  of  oxidation  was  observed  microscopically.  The 
exfoliation  of  the  cubes  was  clearly  seen  during  the 
decomposition  of  the  pyrites,  and  the  residue  of  oxide 
of  iron  assumed  a  spongy  condition,  showing  minute 
threads  and  films  of  gold  interwoven.  As  the  oxidation 
was  proceeded  with,  and  the  temperature  increased,  the 
threads  and  films  could  be  seen  gradually  drawing 
together,  until  they  formed  one  little  speck  of  gold. 
The  experiment  would  point  to  the  same  natural 
process  as  that  taken  advantage  of  in  the  kernel  roast- 
ing of  copper  ores,  wherein,  after  roasting,  the  oxide 
of  iron  in  the  lump  is  found  to  be  altered  until  it  sur- 
rounds a  globule  of  rich  sulphide  of  copper.  However 
satisfactory  the  experiment  was,  as  explaining  the  action 
of  roasting  on  pyrites,  it  is  not  one  which  can  be  lightly 
undertaken,  for  after  being  tried  four  or  five  times  with 
excellent  results,  it  was  found  that  some  portion  of  the 
process  so  affected  the  objective  of  the  microscope  as  to 
destroy  the  definition  and  render  valueless  a  lens  worth 
some  three  or  four  pounds. 

B  3.  Base  minerals  associated  with  the  gold  invariably 
coat  the  surfaces  of  gold  particles  to  a  large  per- 
centage of  the  total  quantity  contained  in  the  ore, 
and  also  give  rise  to  complicated  chemical  reactions ; 
the  effect  of  either  or  both  actions  is  to  prevent 
amalgamation  and  allow  the  gold  to  be  carried  into 
tailings  or  down  stream. 


Losses.  61 

The  losses  detailed  under  head  A  4  will  in  many 
instances  be  identical  when  examining  this  case.  In  the 
first  case  they  may  arise  from  artificial  causes,  that  is  to 
say,  causes  apart  from  the  nature  of  the  ore ;  here  they 
may  arise  from  similar  sources,  added  to  detrimental 
effects  produced  by  constituents  of  the  ore  itself.  In 
Ure's  Dictionary,  Supplement,  the  following  is  recorded 
as  the  result  of  Mr.  J.  Cosmo  Newbery's  investigations 
in  Australia  : 

.  .  .  .  :  It  must  be  remembered,  however,  that  in  some  of  our  quartz 
veins,  native  silver,  native  copper,  native  antimony,  and  native  bismuth 
occur,  and  these  may  so  reduce  the  value  of  the  amalgam,  or  interfere 
with  amalgamation,  so  as  to  lead  to  the  inference  that  there  has  been 
neglect  or  fraudulent  attempt  to  cause  loss  to  the  quartz  miner. 

Gold  containing  arsenic  is  more  difficult  to  amalgamate  than  pure 
gold.  If  much  arsenic  is  present  the  amalgam  is  powdery  and  black, 
and  floats  on  the  surface  of  the  mercury  ;  the  black  colour  is  due  to  the 
separation  of  the  arsenic.  This  black  powdery  metallic  arsenic  does  not 
unite  at  ordinary  temperatures  with  mercury  to  form  an  amalgam,  but 
it  mixes  with  it,  coating  each  globule  with  the  black  powder,  thus  pre- 
venting their  uniting  with  each  other,  or,  in  other  words,  causing  the 
mercury  to  flour.  Sodium  amalgam  aids  the  union  of  mercury  floured 
by  metallic  arsenic,  but  if  arsenious  acid  (common  white  arsenic)  is 
present  it  reduces  it  to  the  state  of  metallic  arsenic. 

Arsenical  pyrites  act  seemingly  in  the  same  way  as  metallic  arsenic 
with  mercury ;  when  ground  with  it  a  large  amount  of  black  floured 
mercury  is  produced.  If  the  pyrite  is  partially  decomposed,  this  action 
is  more  energetic  than  with  the  original  mineral.  I  could  detect  no 
actual  combination  with  the  mercury.  The  black  coating  was  examined 
under  a  microscope,  but  only  seemed  to  be  a  mixture  of  pyrites,  grains, 
and  globules  of  mercury,  both  very  finely  divided.  When  the  mercury, 
covered  thinly  with  this  black  coating,  is  warmed,  the  coating  is  ab- 
sorbed into  the  mass  and  is  liberated  again  as  the  mercury  cools. 

Sulphide  of  antimony   is  perhaps  the  worst  mineral  with 

which  the  quartz  crusher  has  to  deal.  It  divides  the  mercury  into  a 
black  flour  even  more  quickly  than  arsenical  pyrites,  and  if  this  flour  is 
triturated  with  the  intention  of  bringing  the  globules  of  mercury 
together,  a  chemical  combination  takes  place.  The  mass  gradually 
changes  colour,  passing  from  the  original  blue-black,  or  dark-grey,  to 
a,  pure  black,  and  then  through  brown  to  a  brown-red.  Upon  exami- 


62  Losses. 

nation  I  found  that  the  remaining  mercury  contained  antimony,  and  that 
the  brown-red  non-metallic  portion,  consisted  of  mixture  of  undecomposed 
sulphide  of  antimony  and  sulphide  of  mercury. 

Sodium  amalgam  was  found  to  be  worse  than  useless  in  bringing  the 
globules  of  mercury,  floured  by  sulphide  of  antimony,  together.  When 
only  containing  a  small  percentage  of  sodium  it  had  no  action,  and 
when  made  stronger  (sufficient  sodium  to  cause  only  a  slight  evolution 
of  hydrogen  when  the  mercury  was  placed  in  water)  it  decomposed  the 
sulj.  ide  of  antimony,  forming  sulphide  of  sodium,  an  amalgam  of 
antimony  and  mercury  and  sulphuretted  hydrogen.  Sodium  amalgam 
also  reduces  the  metal  from  an  oxide  of  antimony. 

Bismuth the  sulphide  causes  the  quicksilver  to 

separate  into  flour,  and  gives  rise  to  loss  in  the  same  way  as  the  other 
sulphides. 

Lead. — This  metal  has  a  highly  detrimental  influence  in  the  process, 
of  amalgamation,  and  is  often  supposed  to  be  used  for  fraudulent  pur- 
poses, as  a  small  quantity  added  to  mercury  will  cause  a  loss  of  gold 
amalgam  and  mercury  owing  to  the  lead  amalgam  rising  to  the  surface 
of  the  mercury  as  a  frothy  scum  and  carrying  with  it  any  gold  amalgam 
that  may  be  present,  and  by  forming  a  coating  over  the  mercury  prevents, 
its  taking  up  any  gold  that  may  pass  over  its  surface.  The  lead  amalgam 
when  thus  brought  to  the  surface  is  easily  broken  up  and  carried  away 
in  a  fine  state  of  division  by  the  stream  of  water  passing  over  it.  The 
whole  of  the  lead  amalgam  does  not  rise  to  the  surface  at  once,  and 
cannot  be  completely  removed  from  mercury  by  simple  skimming,  but 
the  more  the  mercury  holding  it  is  agitated  the  quicker  it  rises.  The 
only  way  to  completely  remove  lead  from  mercury  is  by  careful  dis- 
tillation. 

B  4.  The  partial  decomposition  of  base  minerals  in 
refractory  ores  produce  acidulated  water,  and  its 
tram  of  attendant  evils  which  act  deleteriously  in 
amalgamation,  causing  granulation  of  the  mercury 
(sickening  or  flouring),  which  prevents  the  particles 
from  re-uniting,  leaving  them  in  a  condition  to  be 
readily  carried  by  water ;  gold,  amalgam,  and 
mercury  are  then  in  the  best  possible  condition  to  be 
carried  off  by  the  water  into  the  tailings  or  down  the 
stream. 


Losses.  63 

The  reason  of  the  partial  decomposition  of  sulphides, 
&c.,  contained  in  ores  has  been  dealt  with  under  head  A 4, 
and  the  production  of  acidulated  water,  and  the  effect 
produced  explained.  When  dealing  with  "  refractory  " 
ores,  all  the  ill  effects  set  forth  under  the  previous  head 
are  likely  to  be  felt,  but  those  which  are  caused  by  the 
nature  of  the  ore  are  certain  to  be  in  an  intensified  fojip. 
With  what  are  known  as  "  free  milling "  ores,  the 
ill-conditions  arising  from  decomposing  mineral  con- 
stituents may  frequently  be  absent.  Yet  in  the  case  of 
"  refractory  "  ores  they  are  invariably  present  to  a  more 
or  less  ruinous  degree.  To  enter  into  the  losses  under 
this  head  would  be  to  reiterate  the  greater  part  of  what 
has  been  written  under  A  4. 

B  5.  The  mechanical  effect  of  heavy  mineral  particles 
in  the  ore,  falling  through  the  stream  of  water,  pre- 
vent contact  between  the  amalgamating  surfaces, 
and  eventually  cut  off  and  clean  the  amalgam  and 
mercury  from  the  plates,  causing  loss  of  gold 
amalgam  and  mercury. 

As  already  mentioned  under  head  A  6,  minerals  of 
the  nature  of  scorodite,  heavy-spar,  &c.  &c.,  are  some- 
times present  in  auriferous  ores  ;  where  so  occurring, 
they,  most  generally,  greatly  exceed  in  quantity  the 
metallic  contents.  The  gravity  of  such  minerals  exceed- 
ing considerably  those  of  the  silicious  and  argillaceous 
portions  of  the  ore,  they  fall  through  a  stream  of  water 
strong  enough  to  carry  off  crushed  rock,  earth  and 
refuse,  therefore  they  speedily  form  a  moving  layer 
which  covers  the  plates  and  prevents  contact  between 
the  gold  and  mercury ;  their  continued  action  cut  the 
amalgam  and  mercury  from  the  plates,  and  these  are 


64  Losses. 

carried  away  by  the  water,  together  with  the  fine  gold. 
In  certain  highly  silicious  ores,  or  where  by  calcination 
the  gangue  has  been  rendered  clean  and  sharp,  a  like 
effect  in  stripping  the  plates  is  produced  to  that  caused 
by  heavy  mineral  contents.  The  effect  of  adding 
additional  water  in  endeavouring  to  remedy  the  defect 
frequently  results  in  refuse,  rock,  mineral,  metal,  and  all 
else  being  carried  away. 

C.  LOSSES  OF  MERCURY. 

Continuous  stamping,  agitation,  or  grinding  causes 
mercury  to  form  into  minute  globules;  these  have 
the  property  of  collecting  Jine  films  of  matter  and 
air  particles  on  their  surface,  which  reduce  their 
relative  weights,  prevents  their  reunition,  and  they 
are  thus  in  a  condition  to  be  readily  carried  off  by 
water  into  tailings  or  down  stream. 

The  effect  of  sulphur,  arsenic,  antimony,  zinc,  grease, 
organic  impurities  in  water,  &c.,  in  rendering  mercury 
impure  and  destroying  its  property  of  coalition 
have,  together  with  other  causes  of  loss,  been  dealt 
with  under  heads  A  5,  6,  and  B  3,  4,  5,  when  referring 
to  the  loss  of  amalgam.  Losing  amalgam  results 
in  a  double  loss,  that  of  gold  and  mercury ;  yet  much  of 
the  latter  is  frequently  carried  away  before  it  has  taken 
up  any  gold  ;  the  losses,  however,  are  so  closely  allied 
that  it  is  almost  impossible  to  draw  a  dividing  line  be- 
tween them. 

If  mercury  is  brought  into  contact  with  any  finely 
ground  material  its  surfaces  become  immediately  coated. 
If  at  the  same  time  a  grinding  or  rubbing  action  is 
carried  on,  the  metal  rapidly  loses  all  its  former  appear- 
ance and  assumes  that  of  the  fine  material  with  which  it 


Losses.  65 

is  mixed.  In  such  a  case  retorting  is  about  the  only 
method  of  bringing  it  back  to  its  original  condition.  In 
some  cases  it  cannot  be  returned,  because  the  action  in 
the  retort  also  affects  the  material  coating  its  globules  or 
particles,  and  results  in  forming  a  chemical  compound. 
The  druggists'  stuff,  Ryd:  ~&  Creta,  commonly  known  as 
"grey  powder/'  is  simply  the  result  of  the  grinding 
together  of  chalk  and  mercury  ;  mercurial  ointment,  its 
admixture  with  a  lard.  The  slimes  produced  by  crushing 
machines,  run  with  water,  frequently  become  almost  as 
greasy  as  lard,  and  the  action  of  crushing  and  pulverising 
machines,  is  invariably,  in  a  greater  or  less  degree,  that 
of  the  pestle  and  mortar  used  by  the  chemist  to  make 
both  "  grey  powder  "  and  mercurial  ointment. 

When  these  properties  are  known  it  ceases  to  be  a 
matter  of  wonder  why  such  difficulties  are  experienced 
in  preventing  loss  of  the  metal.  Every  miner  knows 
when  amalgamating  and  washing  a  prospect  how  hard  it 
is  to  get  together  the  finely  divided  grey-coloured  quick- 
silver in  the  bottom  of  a  pan. 

The  money  value  of  the  mercury  lost  is  not  great,  but 
it  is  the  consequent  loss  of  the  gold  following  that 
makes  the  consideration  of  its  properties  most  essential. 


66  Remedies, 


CHAPTER  V. 

REMEDIES. 

IT  is  but  citing  a  truism  to  assert,  that  any  method  for 
whatsoever  purpose  applied  by  man,  which  has  in  it  a 
feature  working  in  disregard  of  some  natural  law,  must 
prove  a  greater  or  less  failure,  just  to  the  extent  that  it 
contravenes  the  particular  law  involved.  In  the  applica- 
tion of  the  methods  described  for  the  extraction  of  gold 
from  surroundings,  failure  has  followed  and  still  follows 
in  like  proportion.  During  the  early  part  of  the  present 
century  several  notable  teachers  of  the  science  of  metal- 
lurgy sought  for  and  advocated  other  methods  of  treating 
complex  gold  bearing  ores.  About  forty  years  ago  the 
question  again  received  a  great  stimulus,  then  for  the 
first  time  it  was  proposed  for  their  treatment  to 
follow  as  closely  as  possible  a  course  similar  to  that 
daily  carried  on  by  natural  forces,  as  already  de- 
cribed  on  pages  8-11.  Very  little  of  the  researches  of  the 
past  generation  are  generally  known  by  the  present ;  in 
fact,  as  it  will  appear,  even  those  who  are  supposed  to 
have  this  knowledge  possess  little  or  no  information  on 
the  subject ;  this  is  the  only  inference  which  can  be 
drawn  from  the  records  of  the  solvent  processes  patented 
during  the  past  forty  years. 

From  forty-five  years  back  to  the  present,  the  teachers, 
workers,    and   patentees   appear  to   havp  followed  each 
other  in  the  order  set  out  below  : 
1845,  Eisner,  L.,  Chemist,  Berlin. 
1843,  Bagration,  Prince  Pierre,  St.  Petersburg. 


Remedies  67  • 

1848,  Percy,  Dr.  John,  F.R.S.,  London. 

1848,  Plattner,  Carl  Frederick,  Assay  Master,  Royal  Freiberg  Smelt- 
ing Works. 
1848,  Coster,  Apothecary,  Patschkau.* 

1848,  Dufios,  Dr.,  Professor  of  Chemistry,  Breslau. 

1849,  Lange,  Herr,  Master  Smelter,  Reichenstein. 
1849,  Georgi,  Manager  of  Works,  Reichenstein. 
1849,  Richter,  Professor  of  Chemistry,  Leipzig. 

1851,  Guettler,  Exhibitor,  Exhibition,  1851,  London. 

1852,  Spicker,  Charles,  Patentee,  U.S.A.,  No.  8729. 

1857,  Primard,    Edouard,    of   Paris,   Patentee,    Great    Britain,    No. 

1931. 

1858,  Deetken,  G.  F.,  Nevada,  Cal.,  Introduced,   U.S.A.    (see  Kus- 

tell's  Chlorination). 

1859,  Henderson,  Wm.,  Patentee,  Great  Britain,  No.  883. 

1859.  Toussaintand  Laiiglois,  of  Paris,  Patentees,  Great  Britain,  No.. 
956. 

1862,  Cobley  and  Wright,  Patentees,  Great  Britain,  No.  1005. 

1863,  Deetken,  G.  F.,  Nevada,  Cal.,  Patentee,  U.S.A.,  No.  37,278. 

1864,  De  Lacy,  A.  C.  L.,  Melbourne,  Patentee,  Victoria,  No.  fjf. 
1868,  Calvert,  F.  Crace,  F.R.S.,  Bath,  British  Association  Reports. 
1871,  Phillips,  J.  S.,  "Metallurgist's  Companion,"  SanJFrancisco. 

1874,  Dahne,  J.  F.  W.,  Swansea,  Patentee,  U.S.A.,  No.  159,647. 

1875,  Cobley,  T.  H.,  Glasgow,  Patentee,  U.S.A.,  No.  174,118. 
1877,  Mears,   Dr.   J.    J.    H.,    Philadelphia,    Patentee,    U.S.A.,   No.. 

195,381. 

1879,  Mears,  Dr.  J.  J.  H.,  Philadelphia,  Patentee,   U.S.A.,  Re-issue,. 

No.  8859. 

1880,  Mears,  Dr.  J.  J.  H.,  Philadelphia,  Patentee,  U.S.A.,  Re-issue,. 

No.  9203. 
1880,  Schaeffer,  C.  A.,  Patentee,  U.S.A.,  No.  267,723. 

1880,  Mears,    Dr.    J.    J.    H.,    Philadelphia,   Patentee,    U.S.A.,  LNo. 

269,441. 

1881,  De  Figaniere,  of  Philadelphia,  Patentee,  U.S.A.,  No.  267,842. 

1882,  Evans,  N.  F.,  of  Philadelphia,  Patentee,  Great  Britain,  No.  1063, 
1884,  Munktell,  Henrik,   of   Sweden,    Patentee,   Great  ^Britain,  No. 

16,135. 
1886,  Hargreaves  and  others,  Lancashire,  Patentees,  Great  Britain,. 

No.  5681. 
1886,  McArthur  and  others,  Glasgow,  Patentees,  Great  Britain,  No. 

11,817. 

*  These  records  cannot  be  found. 


-  68  Remedies. 

1886,  Hannay,   J.    B.,   Dumbarton,    Patentees,  Great    Britain,  -No. 

14,061. 

1887,  Newbery  and   Vautin,  of  Melbourne,  Patentee,  Great  Britain, 

No.  4609. 
1887,  McArthur  and  others,  of  Glasgow,  Patentee,  Great  Britain,  No. 

14,174. 
1887,  Vautin,  C.  T.  J.,  London,  Patentee,  Great  Britain,  No.  15,574. 

1887,  Pollok,  J.  H.,  Glasgow,  Patentee,  Great  Britain,  No.  17,495. 

1888,  Crookes,  Wm.,  London,  Patentee,  Great  Britain,  No.  7867. 

The  records  of  the  foregoing,  as  will  be  seen,  are 
almost  entirely  confined  to  solvent  processes ;  were  the 
list  allowed  to  embrace  others  it  would  become  inter- 
minable, because  the  records  of  smelting,  electrolytic,  and 
mechanical  methods  far  exceed  in  number  and  ramifica- 
tions those  of  the  solvent  processes.  The  work  done  by, 
or  the  proposals  of  each  investigator,  worker,  or  patentee 
will  be  briefly  summarised,  following  in  the  order  of  their 
dates. 

BAGRATION,  1843. 

In  1843,  Prince  Pierre  Bagration,  working  in  St. 
Petersburg,  appears  to  have  been  the  first  to  have  used 
cyanide  of  potassium  in  a  process  for  dissolving  gold.^ 
He  refers  to  the  older  methods  of  Elkinton  (London), 
who  used  a  double  cyanide  of  potassium  and  iron  as  a 
dissolving  medium,  and  Jacobi,  who  used  ferrous  cyanide 
for  the  same  purpose. 

ELSNER,  1845. 

In  1845,  L.  Eisner,  a  German  chemist,  separated 
gold  from  arsenic  and  tin  by  treating  the  hot  dry 
material  with  a  current  of  dry  chlorine  gas.-f-  He 

*  Bullet  de  1'Acad.  imp.  des  sciences,  St.  Petersburg,    1843,  vol.  ii. 
page  146. 

f  Journal  fur  prakt  Chem.,  vol.  xxxv.,  pp.  310-12,   1845. 


Remedies.  69 

refers  tc  Rosa,  of  Berlin,  who  in  1830,^  advocated 
this  method  for  the  separation  of  sulphur,  arsenic, 
tellurium,  &c.,  from  gold  and  other  metals.  The  method 
had  previously  been  advocated  by  chemists  in  the 
early  part  of  the  present  century.  Eisner  remarks 
that  tin  and  arsenic  volatilize  as  chlorides  but  that  gold 
and  platinum  do  not,  and  therefore  remain  when  other 
metals  are  carried  off. 

PERCY,  1848. 

Tn  the  year  1848f  Dr.  John  Percy,  F.R.S.,  of  London, 
at  the  Swansea  meeting  of  the  British  Association  held 
in  the  month  of  August,  read  a  paper  on  the  extraction 
of  silver  from  ores  by  chlorine,  also  embodying  some 
important  suggestions  as  to  the  value  of  chlorine  as  a 
means  of  extracting  gold;  in  the  experiments  detailed, 
both  gold  and  silver  were  extracted  from  the  ore  treated 
by  means  of  chlorine.  The  paper  details  a  number  of 
highly  interesting  experiments.  J 

*  Handbuch  der  analytischen.  Chemie,  1830,  Griffin's  English  trans- 
lation of  same,  1831. 

f  As  these  experiments  were  made  public  in  the  same  year  as  other 
important   researches   on   the    subject,    the    author,    in   endeavouring 
to  place  the  records  in  their  proper  order,  wrote  to   Dr.   Percy  and  re- 
ceived the  following  reply  : 
Dear  Sir, 

I   duly  received  your  letter  of  the   17th  inst I  can  with 

absolute  certainty  say  that  my  experiments  on  chlorine  were  carried 
out  quite  independently  of  any  suggestions  made  at  the  time  by  the 
German  chemists.  Until  I  read  your  letter  I  was  not  aware  of  the 
experiments  made,  as  you  say,  by  several  German  chemists  in  1848-9.  ... 

Yours  very  truly, 

November  21st,  1888.  John  Percy. 

The  author  was  subsequently  permitted,  by  the  courtesy  of  Dr.  Percy, 
to  search  his  old  chemical  journals,  and  a  record  of  the  carrying  out  of  the 
experiments,  forming  the  paper  read  at  the  1848  meeting  of  the  British 
Association,  appear  between  the  dates  3rd  and  13th  November,  1846. 

J  "Philosophical  Magazine,"  1853,  vol.  xxxvi.,  pages  1-8. 


70  Remedies. 

In  experimenting  on  the  extraction  of  silver  with 
chlorine,  the  ore  dealt  with  was  an  "  auriferous  silver  ore, 
which  contained  a  large  proportion  of  blende,  with 
galena,  iron  pyrites,  and  copper  pyrites  in  small  quantity; 
the  non-metallic  part  chiefly  consisting  of  silica.  The 
silver  was  present  as  sulphuret."  Dr.  Percy  roasted 
this  ore  in  every  case.  In  one  of  the  experiments  he 
powdered  the  ore  finely,  and  put  1000  grains  in  a 
glass  bottle  with  water,  and  passed  chlorine  gas  into 
it  for  one  hour,  closed  tightly,  and  shook  it  up  occasion- 
ally during  four  days,  then  filtered  and  reduced  the 
solution  considerably  by  evaporation,  and  added  hypo- 
sulphite of  soda.  He  then  treated  the  residual  ore  with 
hyposulphite  of  soda,  filtered  and  washed,  and  mixed  the 
"filtrate  with  the  previous  solution;  he  added  hydrochloric 
acid  and  digested,  and  afterwards  got  a  red-brown 
precipitate,  this  he  cupelled  and  obtained  a  button  of 
metal,  and  subsequently  parted  the  gold  from  the  silver 
by  nitric  acid.  He  remarked  that  he  thought  with 
proper  appliances  it  would  be  a  good  process  for  workings 
on  a  large  scale,  then  finally  summarised  as  follows : 

I  would  especially  direct  attention  to  chloride  of  lime  and  chlorine 
as  agents  for  the  conversion  of  the  silver  into  chlorides,  and  to  hypo- 
sulphite of  lime,  which  may  be  readily  obtained  as  a  cheap  substitute 
for  hyposulphite  of  soda  to  dissolve  the  chloride.  The  silver  it  is 
obvious  might  be  precipitated  either  as  a  metal  or  sulphuret. 

Since  many  of  the  South  American  silver  ores  contain  gold,  it  is 
desirable  that  the  silver  and  gold  should  be  extracted  by  one  process  ; 
and  to  this  end  chlorine  or  chloride  of  lime  seems  to  be  indicated  by 
the  preceding  experiments. 

PLATTNER,   1848. 

It  is  not  an  easy  matter  to  define  precisely  the  part 
taken  by  Carl  Fredrich  Plattner  in  devising  the  process 
•of  chlori  nation  which  has  for  so  many  years  borne  his 
name,  or  the  amount  of  credit  due  to  him  for  the  dis- 


Remedies.  71 

covery.  It  would  seem  that  he  carried  out  some  experi- 
ments, to  which  he  attached  little  importance,  so  little 
indeed  that  he  did  not  publish  them  or  make  them 
known,  and  had  it  not  been  that  Mr.  Websky  (a  student 
at  the  Freiberg  Mining  Academy)  communicated  the 
results  to  the  authorities,  the  matter  might  have,  as  far 
as  Plattner  was  concerned,  ended  there;  but,  as  it  turned 
out,  these  particular  experiments  led  to  detailed  investi- 
gations by  other  chemists,  and  that  to  them  are  due  the 
credit  of  further  practical  experiments  from  which  the 
subsequent  devising  of  a  process  resulted.  Plattner's 
name  is  placed  in  this  order  because  the  German 
authors  writing  about  this  date,  mention  that  he 
had  made  certain  investigations,  and  as  a  result  they 
were  carrying  out  experiments  as  to  the  proper  method 
of  applying  chlorine  for  the  purpose  of  extracting  gold 
from  ores.  Professor  Plattner  was  a  metallurgist  of 
great  repute ;  his  works  on  the  blowpipe  and  general 
metallurgical  subjects  are  to-day  standard  works  of 
reference ;  he  held  the  official  position  of  Assay  Master 
at  the  Royal  Freiberg  Smelting  Works.  His  "  Die 
Probirkunst  mit  dem  Lothrohre,"  Leipzig,  1835,  contains 
no  reference  to  chlorination,  although  for  testing  poor 
ores  and  mattes  for  gold,  a  process  -of  roasting  and  subse- 
quent treatment  with  hydrochloric  acid  is  mentioned, 
pages  291-3.  His  next  work  did  not  appear  until  1853, 
his  reference  to  chlorination  in  this  will  be  given  in  full, 
later  on.  In  his  "  Die  Metallurgischen  Rostprozesse," 
Freiberg,  1856,  when  writing  on  the  practical  treatment 
of  ores  by  chlorination  on  a  large  scale,  he  refers  on  page 
274  to  the  "very  complete  researches  on  the  subject, 
undertaken  by  master  smelter  Lange"  (Karsten's  Archiv, 
vol.  24,  p.  396  and  B.u.h.,  1852,  p.  169),  these  also 


72  Remedies. 

will    be    detailed   on    pages    77    to    83  in  their  proper 
order. 

In  1848,  Dr.  Duflos,  of  Breslau,  made  a  series  of 
experiments  which  are  detailed  in  "  Die  schles.  Gesell. 
Uebersicht,"  1848,  pages  27-9  ;  int  his  paper  he  casually 
referred  to  previous  experiments  which  had  been  carried 
out  at  Freiberg,  and  later  on  in  the  paper  acknowledges 
the  previous  experiments  of  Coster,  and  other  experi- 
ments at  Tarnowitz  and  Friedrichshlitte.  In  the  " Journal 
fur  praktische  Chemie,"  vol.  xlviii.,  pages  68-70,  this 
paper  by  Dr.  Duflos  is  reprinted  in  the  form  of  an 
editorial,  without  any  reference  being  made  to  the  original 
source.  Again,  in  the  "Jour,  fur  prak.  Chem.,"  1849, 
vol.  li.,  page  151,  Theo.  Bichter  wrote  as  follows  : 

The  use  of  chlorine  water  for  the  extraction  of  gold  from  poor 
auriferous  ores  was  first  suggested  in  1848  by  Plattner,  of  Freiberg, 
after  he  had  made  experiments  on  a  small  scale  and  had  sufficiently 
satisfied  himself  of  the  usefulness  and  adaptability  of  the  method. 
Plattner  made  his  experiments  with  residuals  of  the  roasting  process 
containing  arsenic ;  these  were  obtained  from  Reichenstein,  in  Silesia, 
by  the  kindness  of  Mr.  Websky,  who  was  then  studying  at  the 
Freiberg  Mining  Academy.  .  .  .  As  these  residues  contain  only  a  very 
small  quantity  of  gold  (probably  only  from  •£%  to  ^  loth  per  cwt.)* 
they  cannot  be  economically  worked  by  any  smelting  process.  These 
residues  had  accumulated  in  large  quantities,  and  it  was  of  great 
importance  to  extract  the  gold  from  them  by  a  rapid  and  cheap  method. 
After  Plattner  had  satisfied  himself  by  qualitative  analysis  that  these 
residues  consisted  chiefly  of  a  mixture  of  oxide  of  iron,  peroxide  of 
iron,  and  basic  arsenical  iron  oxide,  he  treated  the  same  without  any 
other  preparation  in  a  large  closed  retort  with  fresh  chlorine  water, 
and  he  succeeded  in  extracting  in  his  first  experiment  T^-  loth  per  cwt., 
and  in  his  second  experiment  improved  this  to  T\  loth.  These 
experiments  are  the  same  which  are  casually  referred  to  on  page  68  of 
vol.  xlviii.  of  this  journal,  as  having  been  conducted  in  Freiberg 
for  extracting  gold  by  this  process.  It  was  these  experiments, 
the  successful  results  of  which  Mr.  Websky  mentioned  to  the 
author  at  the  time,  which  were  the  cause  of  other  experiments  being 

*  3000  loth  =  1  cwt.. 


Remedies.  7& 

carried  out  on  a  larger  scale  both  in   Reichenstein   and  other  places 
showing  the  practical  utility  of  Mr.  Plattner's  method. 

The  foregoing  is  the  only  reference  to  Plattner's- 
original  experiments  which  can  be  found,  and  even 
this  suggested  reference  is  very  ambiguous.  It  is 
possible  that  in  some  old  German  literature,  or 
in  some  unpublished  paper,  Plattner  wrote  of  his 
discovery  at  the  time,  but  an  exhaustive  search  in  nearly 
all  the  public  and  scientific  libraries  in  London  has 
failed  to  reveal  it,  and  application  a  few  weeks  ago 
through  Mr.  Alfred  Borns,  of  Habelschwendt,  in  Silesiay 
to  the  authorities  of  the  Mining  Institute  of  Tarnowitzr 
has  produced  no  more  satisfactory  result.  German  authors 
do  not  appear  to  have  been  more  successful,  for  in  Karsten, 
Kerl,  and  others  (in  all  of  which  most  elaborate  references 
are  given),  whenever  Plattner  is  referred  to  for  chlori- 
nation,  it  is  simply  by  name  alone,  or  the  later  reference 
of  "  Probirkunst,  1853."  It  would  in  a  measure  destroy 
the  sequence  of  the  story  to  give  this  reference  here  ;  it 
will  appear  on  pages  89-93  in  the  order  of  its  date. 

DUFLOS,  1848. 

Dr.  Duflos,  of  Breslau,  a  chemist  of  note,  who  wrote 
largely  from  the  years  1828  to  1855,  carried  out  a  series 
of  experiments,  under  the  auspices  of  the  Royal  Ober- 
Prasidum,  for  the  purpose  of  seeing  whether  practical 
metallurgical  operations  for  gold  could  be  carried  out  on 
the  Reichenstein  arsenical  residues.  A  free  digest  of  the 
paper  read  by  Dr.  Duflos  on  the  26th  December,  1848, 
at  a  meeting  of  "  Die  schles.  Gesell.  fur  vaterlandische 
cultur,"  detailing  his  experiments,  is  as  follows  : 

In  the  first  place,  to  satisfy  himself  that  it  was  feasible 
experimentally,  he  put  1 5  Ib.  residues  and  15  Ib.  of  water 


74  Remedies. 

into  a  glass  bottle,  leaving  one  quarter  of  it  empty,  this 
lie  filled  with  chlorine  gas,  then  tightly  closed  the  bottle 
with  a  glass  stopper  and  rolled  it  up  and  down  a  table 
for  two  hours.  He  then  removed  the  liquor  by  a  suction 
tube  and  again  twice  treated  the  residues  in  the  bottle 
in  the  same  manner.  The  solid  matter  was  put  into 
three  conical  funnels  placed  over  glass  cylinders,  but  first 
of  all  the  stems  were  filled  with  a  filter  of  coarse  and  fine 
sand.  The  stuff  in  the  funnels  was  then  twice  washed 
with  chlorine  water,  the  combined  liquors  in  the  experi- 
ment were  evaporated  to  ^  Ib.  in  weight,  then  saturated 
with  chlorine  gas  and  filtered,  the  free  chlorine  was 
driven  off  by  warming,  and  the  solution  mixed  with  a 
solution  of  arsenious  acid.  After  twenty- four  hours  the 
clear  liquid  was  poured  off  from  the  deposited  gold, 
which  was  washed  with  hot  distilled  water,  and  dissolved 
in  aqua-regia ;  this  was  poured  into  a  porcelain  dish, 
evaporated  to  dryness,  heated  to  redness,  and  the  gold 
weighed.  To  be  sure  that  his  deductions  were 
correct  he  conducted  this  whole  experiment  a  second 
time  and  got  a  slightly  better  result.  As  a  third 
experiment  he  put  15  Ib.  of  residues  into  three 
glass  funnels,  then  poured  chlorine  water  over  the 
residue  in  the  first  funnel  and  covered  it  with  a  glass 
plate,  when  the  liquor  began  to  drip  through,  the  funnel 
was  refilled  with  chlorine  water,  and  the  quantity  which 
had  dripped  through  was  re-saturated  with  chlorine  and 
poured  into  the  second  funnel.  When  it  had  dripped 
through  this  it  was  again  saturated  with  chlorine  and 
poured  into  the  third  funnel,  the  second  funnel  was 
refilled  from  the  first,  and  so  on,  until  the  operation 
had  been  performed  three  times  on  each  funnel.  The  total 
liquor  then  amounted  to  16  Ib.,  it  was  put  into  an  open 


Remedies.  75 

dish,  and  when  the  chlorine  odour  had  disappeared  it  was 
acidified  with  hydrochloric  acid  and  treated  with  arsenious 
acid  for  precipitation.  After  standing  for  two  days  no 
gold  was  left  in  the  liquor,  which  was  then  evaporated 
to  -^  Ib.  in  weight,  the  precipitate  filtered  out,  washed 
and  dissolved  in  chlorine  w^ater  and  poured  into  an  open 
<lish  ;  where  it  was  evaporated ,  heated  to  redness,  and  the 
gold  obtained.  The  result  was  the  same  as  by  previous 
treatment  in  bottles.  As  a  fourth  experiment  he  re- 
peated the  funnel  operation,  but  instead  of  using  chlorine 
water,  substituted  a  clear  solution  composed  of  1  part  of 
•chloride  of  lime  and  50  parts  of  water  acidified  with 
hydrochloric  acid  ;  the  manipulation  in  this  case  was 
similar  to  that  before,  but  the  difference  in  the  results 
was  insignificant.  As  a  fifth  experiment  solutions  of 
common  salt,  and  common  salt  and  chloride  of  lime  were 
used,  but  from  these  no  results  were  obtained.  Dr. 
Duflos  then  tried  what  he  called  Bagration's  method ; 
he  treated  the  residues  with  a  dilute  solution  of  ferro- 
oyanide  of  potassium,  but  got  no  result.  He  tried 
ferro  cyanide  of  potassium  and  chloride  of  lime,  but  also, 
with  this  mixture,  obtained  no  result.  He  then  re- 
marked that  Liebig's  cyanide  of  potassium  was  not  tried, 
not  so  much  on  account  of  its  high  price  but  because 
the  residues  contained  a  considerable  quantity  of  ferrous 
•oxide  which  would  form  ferro- cyanide  of  potassium, 
and  this,  as  a  solvent,  had  been  already  proved  useless. 
Dr  Duflos  then  pointed  out  that  these  results  agreed 
with  those  obtained  in  Freiberg,  at  the  Friedrichshtitte, 
and  in  Patschkau  by  the  Apothecary  Coster.  Dr.  Duflos 
then  desired  to  ascertain  the  style  of  vessel  which  should 
be  used  for  practical  work ;  with  this  end  in  view  he 
obtained  an  oaken  barrel  which  was  first  soaked  in  ferric 


76  Remedies. 

sulphate  and  then  washed  out  with  milk  of  lime.*  This 
barrel  he  charged  with  15  Ib.  residues  and  30  Ib.  of  dilute 
solution  of  chloride  of  lime  acidified  with  hydrochloric 
acid,  then  closed  the  barrel  tightly  and  revolved  it  on  its 
axis  for  four  hours,  the  liquid  was  then  taken  out  and  put 
into  a  glazed  pot,  the  residues  were  washed  out  of  the 
barrel  with  15  Ib.  of  the  dilute  chloride  of  lime  and  hydro- 
chloric acid  solution.  The  liquor  was  allowed  to  stand 
until  the  sediment  settled  out  of  it,  and  was  then  treated 
as  in  the  previous  bottle  and  funnel  experiments,  and  the 
gold  obtained ;  the  results  from  this  experiment  were 
similar  to  the  foregoing.  A  wooden  vessel  lined  with 
lead,  was  not  tried,  for  the  reason  that  he  thought  the 
action  of  the  lead  would  precipitate  the  gold  chlorides  as 
soon  as  formed,  f  Dr.  Duflos  then  summarised  to  the 
effect,  that  the  percolation  method  extracted  the  same 
amount  of  gold  as  did  the  rotating  bottle  and  barrel, 
which  had  been  proved  by  his  experiments,  also  those  of 
Mr.  Apothecary  Coster  previously  ;|  therefore,  all  things 
considered,  the  percolation  method  was  the  most  satis- 
factory, for  the  cost  of  applying  on  a  large  scale  the 
power  to  rotate  barrels  would  be  considerable.  Also, 
that  at  the  time  of  reading  the  paper,  he  had  no  evidence 
to  show  what  results  would  be  obtained  by  adding  finely 
powdered  manganic  oxide  to  the  residues,  and  subse- 
quently percolating  through  them  a  solution  of  hydro- 
chloric acid,  as  compared  with  treating  the  residues  with 
chloride  of  lime  solutions  acidified  by  hydrochloric  acid. 

*This  evidently  was  for  the  purpose,  and  would  have  the  effect,  of  filling 
the  pores  of  the  wood  with  an  insoluble  substance  such  as  plaster-of-Paris. 

t  Metallic  lead  has  the  effect  of  breaking  up  gold  chlorides  and  pre- 
cipitating the  metal,  but  the  presence  of  chlorine  gas,  as  in  Dr.  Duflos's 
barrel,  prevents  this  precipitating  action. 

;{;  Record  of  these  cannot  be  found. 


Remedies.  77 

He  then  pointed  to  the  small  quantity  of  gold  obtained, 
but  the  results  differed  little  from  the  experiments  at 
Tarnowitz,*  but  considerably  from  those  of  Coster  ;* 
possibly  the  samples  treated  had  been  taken  from  dif- 
ferent positions  or  contained  different  quantities  of  gold, 
or  gold  combined  differently — this  latter  view  being 
especially  supported  by  the  gold  extraction  experiments 
made  in  the  dry  way  at  Friedrichshutte.  * 

Dr.  Duflos's  experiments  were  evidently  carried  out 
solely  for  the  purpose  of  devising  a  suitable  method  of 
treating  the  Reichenstein  arsenical  residues ;  he  abandoned 
the  idea  of  using  a  rotating  barrel  because 'with  the  par- 
ticular residues  under  treatment,  equally  accurate  results 
were  obtained  by  percolation  methods.  This  is  true  as 
regards  several  ores;  nevertheless  there  are  many  cases 
where  vat  chlorination  and  percolation  methods  are 
neither  as  suitable  nor  as  economical  as  the  barrel  pro- 
cess. The  time  occupied  in  treating  the  residues  appa- 
rently did  not  enter  into  Dr.  Duflos's  calculations,  at 
any  rate  he  evidently  did  not  consider  the  saving  in  time 
would  compensate  for  the  cost  of  applying  the  power  to 
rotate  a  barrel  plant.  Even  now,  when  dealing  with  a 
small  supply  of  ore,  the  conditions  of  cost  are,  in  this 
respect,  almost  similar,  but  where  a  large  mass  of  ore  has 
to  be  treated  daily,  the  aspect  of  the  case  becomes  wholly 
different. 

LANGE,   1849. 

In  Karsteii's  "Archiv,"  vol.  xxiv.,  page  396  to  429,  Herr 
Lange's  experiments  are  detailed;  they  are  those  referred 
to  by  Plattner  in  his  "  Rostprozesse,"  page  274,  1856. 
Herr  Lange  stated  that  the  results  obtained  by  Professor 
Plattner,  in  Freiberg,  in  treating  Reichenstein  arsenical 
*  Record  of  these  cannot  be  found. 


78  Remedies. 

residues  by  chlorine,  led  to  his  undertaking  the  following- 
experiments  for  the  purpose  of  determining  upon  a 
practical  commercial  method  of  treating  them.  The 
following  free  digest  of  Herr  Lange's  article  will  show 
sufficiently  all  the  points  of  his  investigations  : 

He  stated  that  the  residues  were  arsenical  roastings, 
containing,  by  Karsten's  analysis,  chiefly  ferrous  and 
ferric  oxides,  highly  minute  quantities  of  gold,  also  some 
arsenic  and  arsenious  acids ;  the  gold  was  free,  white  arsenic 
free,  and  the  arsenic  acid  was  as  a  basic  ferric  arseniate. 
He  worked  on  residues  produced  between  1807  and  1830. 
Previous  to  beginning  his  experiments  he  put  some 
residues  in  a  bottle  with  chlorine  water  and  shook  them 
up,  and  found  that  by  this  means  gold  could  be 
extracted.  Herr  Lange  said  that  Dr.  Duflos,  of  Breslau, 
and  Dr.  Coster,  of  Patschkau,  had  previously  made 
experiments,  and  had  come  to  the  conclusion  that  shaking- 
was  not  necessary  because  percolation  methods  extracted 
the  same  quantity  of  gold.  His  experiments  were  there- 
fore conducted  by  percolation  methods  ;  he  worked  in 
unglazed  sugar  moulds,*  as  he  could  not  get  glazed.  He 
put  some  stones  and  four  inches  of  sand  into  the  bottom 
of  the  sugar  moulds,  then  filled  them  up  with  residues  ; 
the  first  trial  was  with  chlorine  water  prepared  from 
three  parts  hydrochloric  acid  of  1.13  specific  gravity, 
one  part  manganic  oxide,  and  one  part  of  water,  this 
gave  28  parts  of  chlorine  water  (all  parts  in  these 
experiments  are  by  weight).  He  found  it  was  necessary 
to  close  the  holes  in  the  bottom  of  the  sugar  moulds,  so 
that  the  liquor  could  remain  in  contact  with  the  residues, 
otherwise  it  dripped  through  too  fast.  He  proceeded 
with  the  experiment  quantitatively,  and  came  to  the 

*  Zukerhutformen  (sugar-hat-moulds). 


Remedies.  79 

conclusion  that  the  liquor  from  the  residues  was  so 
extremely  poor  in  gold  that  gold  could  not  be  precipitated 
from  it,  for  after  acidifying  with  hydrochloric  acid  and 
using  sulphuretted  hydrogen  as  a  precipitant,  only  an 
opalescence  was  produced,  and  the  liquor  required  a  rest  of 
many  days  to  become  clear  ;  he  concentrated  the  liquor 
by  evaporation  and  obtained  about  50  percent,  of  the 
gold  contained  in  the  ore.  Herr  Lange  then  obtained 
some  glazed  sugar  moulds,  and  substituted  chloride  of 
lime  for  chlorine  water.  For  every  25lb.  of  residues  — 
which  contained  4^  Ib.  of  water — he  used  5^  oz.  of 
chloride  of  lime,  5  Ib.  of  water,  and  1 0  oz.  of  hydrochloric 
acid  ;  this  he  mixed  with  the  residues  and  treated  them  in 
a  manner  similar  to  the  foregoing  experiment.  The  total 
quantity  of  liquor  from  this  experiment  amounted  to 
60  Ib.,  which  was  evaporated  to  lOlb. ;  this  was  seen  to 
contain  a  brown  precipitate  which  he  filtered  out.  As 
the  clear  liquor  was  found  to  contain  very  little  gold, 
the  precipitate  already  filtered  out  was  dissolved  in 
nitric  and  hydrochloric  acids,  from  which,  by  the  aid 
of  sulphuretted  hydrogen,  a  rich  precipitate  of  metallic 
gold  was  obtained,  equal  to  about  55  per  cent,  of 
the  quantity  in  the  ore.  Herr  Lange  then  made  the 
following  deductions  :  "  That  by  the  use  of  chloride 
of  lime,  gold  is  more  completely  extracted,  than 
by  the  use  of  chlorine  water,  and  that  the  former  is 
much  less  injurious  to  the  health  of  the  workmen."  As 
a  third  experiment,  working  with  residues  subsequent 
to  1830,  he  poured  chloride  of  lime  water  into  the 
residues,  then  added  hydrochloric  acid  so  as  to  evolve 
chlorine  within  the  ore  mass,  for  when  mixed  outside 
much  chlorine  gas  escaped.  He  allowed  the  residues  to 
stand  for  five  hours,  then  opened  the  holes  in  the 


80  Hemedies. 

bottom  of  the  vessels,  and  continued  to  pass  the  liquor 
through  the  ore,  but  got  no  better  results.  Winter 
came  on  and  it  was  found  that  chlorine  crystallised 
out  of  the  solutions  at  7  deg.  R.  therefore  lost  its  solvent 
action,  and  it  was  concluded  that  if  the  rooms  were 
closed  and  warmed — as  would  be  necessary  during  the 
winter — the  action  of  chlorine  would  be  very  injurious 
to  the  respiratory  organs.  Herr  Lange  then  removed 
from  Reichenstein  to  a  laboratory  in  Fredrichshlitte, 
near  Tarnowitz,  and  continued  his  experiments.  He  found 
in  working,  when  solutions  were  poured  on  pulverised 
residue,  "  that  in  spite  of  standing  the  whole  day  it  did 
not  sink  into  the  charge,"  therefore  he  took  the  residues 
from  the  open  vessel,  put  them  into  a  closed  one,  and 
agitated  it  during  the  dissolving  process.  He  then  tried 
heating  the  residues,  and  when  raised  to  a  temperature 
of  about  120°  R,  he  put  them  in  the  sugar  moulds,  and 
poured  in  chlorine  water,  allowed  them  to  stand  for  ten 
hours,  and  drained  the  liquor  off,  then  he  poured 
in  a  fresh  lot  of  dissolving  solution  and  let  them 
rest  for  another  eight  hours,  before  the  final  washing ; 
from  this  liquor  he  obtained  from  80  to  90  per  cent, 
-of  the  gold  contained  in  the  ore.  Winter  having 
passed,  Herr  Lange  resumed  work  at  Reichenstein, 
.and  made  a  new  set  of  experiments.  He  used  chloride 
of  lime  solutions  as  more  convenient  and  less  noxious 
than  the  manganic  oxide  and  hydrochloric  acid  method 
of  producing  chlorine ;  he  mixed  1  Ib.  of  chloride  of  lime 
in  lOlb.  of  water,  and,  after  allowing  it  to  stand  for 
twenty-four  hours,  removed  the  clear  liquid  and  decom- 
posed it  either  by  hydrochloric  or  sulphuric  acids.  Two 
-experiments  were  made,  one  with  25  Ib.  and  one  with 
100  Ib.  of  residues  heated  to  80  deg.  R.  ;  these  were 


Remedies.  81 

treated  with  a  large  excess  of  chloride  of  lime  and 
hydrochloric  acid  solution,  of  such  a  strength,  that  a  piece 
of  gold  leaf  put  into  it  completely  dissolved  before 
it  had  sunk  2  in.  in  the  liquid ;  the  whole  of  the  gold  in 
the  residues  was  dissolved  and  recovered.  Comparative 
experiments  were  instituted  with  arsenious  acid  and  sul- 
phuretted hydrogen  as  precipitants,  which  resulted  in 
favour  of  the  latter,  the  former  being  too  slow  for  a 
factory.  Herr  Lange  then  continued  his  experiments 
with  chloride  of  lime  solutions,  using  2f  Ib.  of  chloride 
of  lime  to  lOOlb.  of  residues  ;  10  Ib.  of  this  solution,  after 
being  acidified,  was  poured  over  25  Ib.  of  previously 
heated  and  still  warm  residues  in  the  sugar  moulds,  and 
as  the  impregnation  took  place  very  slowly,  left  un- 
disturbed for  twenty-four  hours ;  he  remarked  that 
operations  on  a  large  scale  should  be  arranged  to  be- 
commenced  on  one  day  and  finished  the  next.  He  found 
that  the  above  quantity  of  chloride  of  lime,  with  subse- 
quent washing  in  hot  water,  quite  sufficient  to  extract  all 
the  gold  ;  hence  3  Ib.  of  chloride  of  lime  with  13.5  per 
cent,  of  active  chlorine,  and  1  Ib.  of  hydrochloric  acid., 
sufficed  for  lOOlb.  of  residues.  He  then  noticed  that 
the  first  4  Ib.  of  drainings  contained  little  or  no  gold  but 
much  arsenic,  &c.,  therefore  concluded  that  the  latter  was 
more  readily  acted  upon  by  the  chlorine  than  was  the 
gold,  and  hoped  that  by  the  previous  removal  of  arsenic., 
&c.,  to  economise  chloride  of  lime.  With  this  end  in 
view  the  residues  were  first  treated  with  hydrochloric 
acid,  then  with  chloride  water,  but  no  beneficial  result 
was  observed,  so  he  concluded  that  the  above 
quantity  of  chloride  of  lime  is  the  minimum  proportion 
which  can  be  used  for  complete  extraction  of  the 
gold ;  he  concentrated  all  his  solutions  by  evaporation, 


82  Remedies. 

and  noted   that   metallic    lead    decomposed    gold    chlo- 
rides. 

At  the  instigation  of  Dr.  Karsten,  Herr  Lange 
instituted  a  series  of  experiments  with  gaseous  chlorine. 
The  ordinary  sample  of  25  Ib.  of  moistened  residues  were 
placed  on  a  filtering  layer  of  gravel,  in  an  inverted 
bottomless  bottle,  a  cork  was  fitted  into  the  neck  and  a 
tube  for  the  chlorine  gas  passed  through  the  cork ;  the 
gas  was  prepared  from  manganic  oxide  and  hydrochloric 
acid.  After  two  hours  of  a  steady  current  the  gas  had 
penetrated  the  mass,  then  after  another  two  hours  it  was 
stopped,  the  residues  .were  then  left  undisturbed  for 
fifteen  hours,  and  afterwards  turned  out  into  the  sugar 
moulds  and  washed,  5  Ib.  of  hot  water  being  found 
sufficient  to  remove  all  the  gold ;  a  great  improvement 
over  13  Ib.  of  water  necessary  in  the  experiments  with 
chloride  of  lime.  Other  experiments  showed  that 
lieating  the  residues  by  means  of  steam,  either  before 
passing  in  the  chlorine  gas  or  after  some  gas  had  been 
passed  in  had  a  deleterious  effect,  and  that  the  use  of 
•chlorine  gas  alone  was  the  most  suitable  for  the 
Keichenstein  works.  Quantitative  experiments  showed 
1  Ib.  of  hydrochloric  acid  to  be  the  minimum  required 
for  25lb.  of  residues  treated  in  the  usual  way.  As  an 
additional  experiment  25lb.  of  residue  was  treated  with 
chlorine  gas  generated  from  1  Ib.  of  hydrochloric  acid  and 
J-  Ib.  of  manganic  oxide ;  this  charge  was  washed  so  as  to 
yield  6  Ib.  of  solution.  Two  pounds  of  this  solution  were 
set  aside  and  the  remaining  4  Ib.  were  used  to  moisten 
a  fresh  charge  of  25  Ib.,  which  was  then  treated  with 
^chlorine  from  %  Ib.  of  hydrochloric  acid  and  ^  Ib.  of 
manganic  oxide ;  by  repeating  this  experiment  twice 
again,  all  the  gold  was  extracted  from  lOOlb.  of  residues 


Remedies.  83 

with  3^1b.  of  hydrochloric  acid  and  about  1^  Ib.  of 
manganic  oxide;  the  total  liquor  from  the  lOOlb.  of 
residues  treated  amounted  to  8  Ib.  He  then  tried 
washing  the  treated  residues  with  water  of  various 
temperatures,  and  found  very  little  difference  in  the 
results  ;  if  anything,  those  from  water  at  normal  tempera- 
ture were  slightly  better.  The  drying  of  the  residues 
and  subsequent  treatment  with  gaseous  chlorine  was  not 
found  to  be  a  profitable  method  of  treatment. 

Herr  Lange  then  concluded  that  it  was  quite  feasible  to 
extract  the  gold,  in  a  commercial  manner,  from  the 
Reichenstein  arsenical  residues  by  means  of  chlorine,  and 
that  best  results  were  obtained  by  the  use  of  gaseous 
chlorine  ;  therefore,  the  projected  works  and  plant  for  gold 
extraction  at  Reichenstein  should  be  erected  for  the  use 
of  gaseous  chlorine.  These  experiments  are  the  "  very 
complete  researches  "  referred  to  by  Plattner  in  his  "  Die 
Metallurgischen  Rostprozesse,"  published  in  Freiberg  in 
1856. 

GEORGI,  1849. 

Herr  Georgi  was  the  manager  of  Guettler's  works 
erected  at  Reichenstein  for  treating  the  arsenical  residues 
by  the  chlorine  process  ;  he  has  written  several  articles 
describing  the  way  in  which  the  work  was  conducted. 
Though  the  matter  was  doubtless  of  much  interest  at  the 
time  when  they  were  written,  being  descriptions  of  what 
was  new,  it  would  be  unnecessary  repetition  to  embody 
them  herein ;  Kerl's  contribution  to  the  subject,  which 
will  follow  in  order,  is  a  description  of  the  works. 

RICHTER,   1849. 
The  following  is  a  translation*  of  the  remaining  portion 

*  The  translation  by  Mr.  G.  M.  Borns. 


84  Remedies. 

of  the  article  by  Theodor  Bichter  which  appeared  in  the 
"Journal  fiir  practische  Chemie,"  vol.  li.,  pages  151-4, 
published  in  January,  1850.  A  part  of  this  article  has 
been  already  quoted  when  first  referring  to  Plattner,  the 
remainder  describes  some  experiments  by  Bichter,  and 
mentions  more  recent  investigations  by  Piattner.  The 
article  is  especially  interesting  as  it  explains  a  method  of 
using  wooden  vessels  in  lieu  of  earthenware. 

The  experiments  on  Reichenstein  ore,  which  were  carried  out  for  a 
considerable  time  in  a  very  thorough  manner,  prove  that  gold  can  be 
extracted  from  poor  residues  with  comparatively  satisfactory  financial 
results.  Since  Mr.  Plattner's  first  experiments  in  his  laboratory  he 
himself,  and  also  the  writer  of  this  article,  have  frequently  repeated 
them,  using  the  same  method  for  the  treatment  of  various  gold  ores, 
especially  those  containing  pyrites ;  these  experiments  have  proved  that 
a  considerable  amount  of  success  had  been  due  to  the  thorough  manner 
in  which  these  ores  had  been  previously  roasted.  If  the  roasting  was 
not  complete,  leaving  some  non-oxidised  particles  of  pyrites,  the  chlorine 
was  very  soon  exhausted  by  the  formation  of  sulphur  and  metallic 
chlorides,  and  the  filtering  fluid  contained  only  traces  of  gold ;  so« 
much  was  this  the  case  with  pyrites  which  contained  a  considerable 
amount  of  zinc,  that  this  metal  was  found  in  considerable  quantities  in 
the  fluid.  The  extraction  of  gold  from  such  ores  in  which  it  occurs  in 
finely  divided  metallic  particles  as  in  quartz  and  so-called  gold  sand  can 
be  carried  on  without  any  difficulty ;  the  only  precaution  necessary 
being  that  whilst  stamping  the  ores  they  should  not  be  mixed  with  too- 
many  particles  of  iron,  since  these  always  exhaust  a  considerable 
quantity  of  chlorine  solution.  When  metallic  iron  is  present  it  is 
advisable  to  heat  the  ore  so  as  to  completely  oxidise  it  but  not  melt  the- 
gold.  Some  practical  difficulties  were  likely  to  arise  on  the  application 
of  this  method  on  a  large  scale  in  the  vessels  used  for  the  purpose,  since- 
neither  wood  nor  iron  vessels  would  be  suitable.  At  Reichenstein 
earthen  vessels  of  the  sugar-loaf  form  were  used  with  considerable 
success ;  whether  they  are  still  used  the  author  does  not  know.  These 
vessels  contained  about  J  cwt,  of  residues,  and  the  extraction  of  gold 
was  carried  out  by  what  may  be  called  the  displacement  method. 
These  vessels  always  suffered  from  the  fault  of  being  easily  broken,  and 
were  only  of  small  capacity.  For  the  experiments  which  Plattner  has 
recently  carried  out  he  used  wooden  vessels  similar  to  those  used  in  the 
Augustine  desilverisation  process.  A  wocden  cross  is  placed  en  the 


Remedies.  85 

bottom  of  these  vessels,  and  upon  this  a  wooden  perforated  disc  ;  all 
surfaces  in  contact  with  the  gases  are  thoroughly  pitched.  Upon  the 
wooden  disc  is  placed  a  layer  of  pure  quartz,  about  J  in.  thick,  as  a 
filter,  all  the  spaces  of  which  are  filled  in  with  quartz  sand  level  with 
the  top ;  the  gold  ore  is  placed  immediately  upon  this,  and  another 
wooden  strainer,  pitched  as  the  first,  is  covered  over  this.  At  the 
bottom  of  the  vessel  between  the  arms  of  the  cross  is  a  glass  tap  for 
drawing  off  the  fluid ;  the  chlorine  water  is  poured  upon  the  top  surface 
of  the  strainer  so  that  it  is  distributed  evenly  over  and  through  the 
whole,  the  tap  meanwhile  being  open,  but  it  is  closed  as  soon  as  the 
fluid  begins  to  flow  regularly  without  any  bubbles,  and  the  chlorine  is 
then  allowed  to  act  upon  the  ore  for  any  required  time,  the  vessel  being 
covered  with  a  thoroughly  pitched  wooden  cover.  The  fluid  finally  runs 
off  perfectly  clear,  and  if  it  contained  free  chlorine  can  be  used  again 
for  further  concentration. 

No  appreciable  difference  in  the  quantity  of  gold  extracted  has  been 
found  when  using  the  pitched  wooden  vessels  or  the  earthenware  ones, 
nor  so  far  has  the  chlorine  gas  attacked  the  wood,  and  it  is  probable 
that  a  similar  plant  might  be  used  on  a  large  scale.  In  these  experi- 
ments the  gold  was  deposited  by  means  of  a  solution  of  sulphate  of  iron 
(vitriol),  care  being  taken  that  any  free  chlorine  should  be  previously 
disposed  of  by  heat.  It  is  possible  in  an  experiment  on  a  larger  scale 
it  might  be  found  profitable  to  use  cement  copper  similar  to  the  process 
of  depositing  silver  in  the  Augustine  method,  or  some  other  still  more 
suitable  material  may  be  found  for  reducing  the  gold. 

GUETTLER,    1851. 

Wilhelm  Guettler  appears  to  have  been  the  licensee,  or 
to  have  had  some  Government  concession  for  working 
the  mines  at  Reichenstein.  At  the  International  Exhi- 
bition held  in  London  in  1851,  W.  Guettler  exhibited 
specimens  of  the  mispickle  ores  (arsenical  pyrites)  which 
he  treated  successfully  by  the  chlorine  method.  These 
specimens  are  still  to  be  seen  in  the  Geological  Museum 
in  Jermyn-street,  London. 

In  the  printed  records  of  this  Exhibition  under  head 
"  Prussia, "  page  1048,  Exhibit  6,  is  the  following  : 

Specimens  of   arsenical  gold,  washed  and  unwashed  ore,1  showing  a 


86  Remedies. 

process  by  which,  out  of  the  residues  of  the  arsenic  ores,  the  gold 
therein  contained  is  chemically  drawn  out  by  moisture. 

The  process  is  grounded  on  the  trials  by  Mr.  Plattner,  professor  of 
chemistry  at  Freiberg,  in  Saxony. 

Guettler  Wilhelm,  Reichenstein,  Silesia. 

In  reporting  on  this  exhibit  the  jury  gave  the  following 
decision,  as  may  be  found  in  "  Report  of  Juries,"  page  5  : 

The  mines  of  Reichenstein,  in  Silesia,  abandoned  for  more  than  five 
centuries,  have  recently  been  opened  with  advantage,  in  consequence  of 
the  application,  on  a  large  scale,  of  a  method  invented  by  Professor 
Plattner  for  separating  gold  from  waste  arsenical  ores. 

The  ore  at  Reichenstein  is  an  arsenical  pyrites,  containing  about  200 
grains  of  gold  in  the  ton.  The  ore  is  roasted  in  a  reverberatory  furnace 
surmounted  by  a  large  condensing  chamber,  in  which  the  arsenious  acid* 
is  condensed  as  fast  as  it  volatilizes.  There  then  remains  on  the  floor 
of  the  furnace  oxide  of  iron  mixed  with  a  certain  quantity  of  arsenic 
together  with  the  whole  of  the  gold.  This  is  placed  in  a  vessel  so 
arranged  that  a  current  of  chlorine  gas  can  be  passed  through  it  by 
which  the  gold  and  iron  are  taken  up  (sic)  and  afterwards  separated 
from  the  residuum  by  the  aid  of  a  certain  quantity  of  water,  and  the 
gold  is  afterwards  precipitated  from  this  solution  by  sulphuretted 
hydrogen.  To  prevent  the  admixture  of  iron  at  this  stage  a  small  dose 
of  hydrochloric  acid  is  added  to  the  solution  before  the  sulphuretted 
hydrogen  is  introduced.  The  ore  compound  having  been  separated 
from  the  liquor,  is  washed  and  heated  in  an  open  porcelain  crucible 
to  drive  off  the  sulphur,  by  which  the  gold  is  reduced  to  the  metallic 
state  by  fluxing  it  in  the  usual  manner. 

This  simple  and  ingenious  method,  which  has  made  it  worth  while  to 
re-open  the  Reichenstein  mines,  is  equally  applicable  to  the  vast  quantity 
of  refuse  accumulated  near  many  old  works.  In  awarding  the  Council 
medal  the  jury  have  desired  in  this  case  to  associate  the  name  of  Pro- 
fessor Plattner,  the  inventor  of  the  method,  with  that  of  Mr.  Guettler 
who  has  brought  it  into  operation  on  a  large  scale. 

In  their  remarks  the  jury  of  this  Exhibition  appear  to 
have  fallen  into  the  same  error  as  several  others  have 
previously  done,  of  crediting  Plattner  with  having 
devised  the  perfected  process.  That  certain  experiments 
of  his  led  to  more  complete  researches  being  instituted, 
*  Common  white  arsenic. 


Remedies.  87 

is,  doubtless,  true,  but  Plattner  himself  points  to  Lange's 
researches,  and  in  the  record  of  Lange's  experiments  Dr. 
Karsten  is  accredited  with  the  suggestion  of  utilizing 
gaseous  chlorine.  The  jury  also  appear  to  be  in  error  as 
to  the  length  of  time  the  Reichenstein  mines  had  been 
closed,  for  Kerl,  in  his  "  Hiittenkunde,"  vol.  iv.,  page 
372,  says  to  this  effect :  The  auriferous  arsenical  pyrites 
deposits  of  Reichenstein  were  utilized  at  the  beginning 
of  the  17th  century  for  the  production  of  gold  simulta- 
neously with  mining  for  galena ;  as  soon  as  lead  mining 
ceased,  so  ceased  also  the  treatment  for  gold,  but  since  the 
middle  of  the  1 8th  century  the  mines  had  been  utilized 
for  the  production  of  arsenic,  and  the  residues  were 
heaped  up  for  future  treatment. 

It  would  seem  that  these  were  the  residues  experi- 
mented upon  and  treated  by  the  chlorine  process.  Were- 
it  otherwise,  and  that  these  residues  had  lain  for  five  hun- 
dred years'  and  still  retained  some  of  their  gold  locked  up, 
it  would  have  been  truly  remarkable.  In  ordinary  cases  a 
few  years'  exposure  will  completely  decompose  the  pyrites 
in  a  heap  of  tailings ;  this  is  so  well  known  that  it  is  cus- 
tomary in  many  countries  to  stack  pyrites  and  wash  them 
occasionally,  and  from  the  fact  of  free  gold  being  obtained 
on  each  washing,  which  was  not  in  that  condition  when, 
previously  treated,  a  superstition  has  arisen  that  gold 
grows  in  pyrites  and  tailings  heaps,  as  though  it  were 
a  plant.  The  remarks  of  the  jury  as  to  the  chlorine 
method  being  applicable  for  the  treatment  of  the  refuse 
accumulating  around  old  works  is  very  much  to  the 
point,  and  had  the  same  hint  been  printed  in  a  more 
widely  read  publication,  perhaps  the  process  would  long 
ago  have  been  more  generally  applied. 

The  description  of  the  works  at  Reichenstein  is  taken- 


88  Remedies. 

from  Kerl's  "  Hiittenkunde,"  vol.  iv.,  pp.  372-76,  1865. 
The  following  is  a  free  digest  of  the  above  which  appears 
In  Kustel's  "  Chlorination,"  1868,  pp.  253-55. 

The  chlorination  works  at  Reichenstein,  Silesia,  were  erected  for  the 
working  of  arsenical  pyrites.  The  gold  is  extracted  by  Plattner's 
chlorination  process.  The  building  contains  forty-eight  earthen  chlori- 
nation pots,  of  which  twenty-four  are  always  charged  with  roasted  ore 
while  the  contents  of  the  other  twenty -four  are  undergoing  chlorination. 
The  pots  are  strengthened  with  iron  hoops,  and  so  prepared  that  for 
discharging  they  can  be  turned  over  on  two  journals.  The  lower  end 
is  conical,  and  contains  an  earthen  perforated  plate.  There  is  a  wooden 
cover  with  a  small  round  hole  in  it,  on  the  top  of  the  pot.  The  gas 
pipe  communicates  with  the  conical  end.  The  gas  generators  are  also 
earthen  pots  with  leaden  covers. 25  Ib.  each,  provided  with  an  opening 
for  the~discharge,  and  with  a  leaden  gas  pipe.  There  are  twenty  glass 
globes,  used  as  precipitating  vessels,  standing  on  a  sand  bath.  There 
are  also  ten  bottles  for  the  production  of  sulphuretted  hydrogen.  The 
conical  part  of  the  chlorination  pots  is  charged  with  small  pieces  of 
quartz  and  covered  with  the  perforated  plate.  After  the  concentrated 
arsenurets  are  moistened  (in  winter  with  warm  water)  each  pot  is 
charged  with  150  Ib.  The  gas  generators  are  covered  and  secured  air- 
tight with  flour  dough,  and  the  gas  pipes  arranged  to  convey  the 
chlorine  into  a  washing  vessel  to  free  it  from  muriatic  acid.  Each 
generator  receives  13  Ib.  muriatic  acid  and  7  Ib.  sulphuric  acid,  diluted 
with  the  same  quantity  of  water ;  and  as  soon  as  the  chlorine  is 
required,  7  Ib.  of  manganese  are  added.  The  charging  hole  is  shut  and 
the  fire  started  underneath  the  sand  bath.  After  the  chlorine  has 
passed  through  the  ore  for  an  hour,  the  pots  are  closed  with  the  covers, 
and  examined  from  time  to  time  to  see  whether  the  chlorine  rises  above 
the  ore.  This  is  the  case  when  a  glass  rod  dipped  in  ammonia  creates 
white  fumes  above  the  hole  of  the  cover.  After  six  to  seven  hours  the 
impregnation  is  finished ;  and  all  the  joints  of  the  cover  and  pot  are 
secured  by  dough,  and  the  chlorine  allowed  to  act  on  the  gold  until 
the  next  day.  The  covers  are  then  taken  off  and  water  of  14  deg.  to 
20  deg.  R.  introduced.  Boiling  water  would  absorb  less  gas  and  dis- 
solve more  salts.  The  leaching  is  stopped  as  soon  as  about  96  cubic 
feet  of  the  lixivium  from  twenty-four  pots  is  obtained  (from  3600  Ib. 
of  ore).  The  lixivium  from  all  the  pots  is  conveyed  into  four  vats, 
beginning  at  the  first,  so  that  the  fourth  vat  receives  the  poorest  leach. 
The  very  small  quantity  of  gold  contained  in  this  is  not  precipitated, 
but  the  fluid  is  used  over  again  for  leaching  the  next  day.  The  fluid 


Remedies.  89 

from  the  other  three  vats  is  drawn  over  into  the  glass  globes  which 
stand  on  a  sand  bath  in  order  to  bring  the  temperature  of  the  contents 
up  to  20  deg.  R.  Sulphuretted  hydrogen  obtained  from  bleistein 
(sulphide  of  lead  obtained  in  smelting  lead  ores)  and  diluted  hot 
sulphuric  acid,  is  conducted  into  the  globes  until  the  fluid  appears 
perfectly  black  from  precipitated  'sulphide  of  gold.  This  remains  warm 
in  the  vessel  until  the  next  day,  when  the  gold  is  found  deposited  on 
the  bottom.  From  each  globe  the  clear  fluid  is  drawn  into  a  filter  by 
means  of  glass  syphons,  the  ends  of  which  can  be  corked  more  or  less 
tightly,  so  that  the  supply  can  be  regulated  according  to  the  capacity 
of  the  filter.  That  which  goes  through  the  filter  is  conveyed  through 
cisterns  filled  with  sawdust,  in  order  to  absorb  any  sulphide  of  gold 
which  may  have  escaped.  The  precipitated  gold  is  finally  washed  into 
the  filters.  In  the  course  of  sixteen  days  320  filters  containing  sul- 
phides of  gold  are  obtained ;  these  are  dried  and  burned  on  four  large 
dishes,  then  boiled  in  aqua-regia,  filtered,  and  the  gold  of  the  filtrate 
precipitated  by  sulphate  of  iron.  The  precipitated  gold  is  placed  upon 
filters  and  washed ;  first  with  diluted  muriatic  acid  and  then  with 
water.  After  this  the  filters  are  dried  and  burned,  and  the  gold  melted 
-with  borax  and  saltpetre  in  clay  crucibles.  The  quantity  of  concen- 
trated arsenurets  daily  subjected  to  chlorination  is  3600  lb.,  containing 
about  f  oz.  of  gold  per  ton,  so  that  not  more  than  from  20  lb.  to  21  lb. 
of  gold  is  extracted  yearly. 

PLATTNER,   1853. 

The  extract  from  Plattner's  "Probirkunst,"  1853,  page 
570,  before  referred  to,  and  the  reference  which  Kerl 
.and  other  German  writers  give  when  quoting  him  as  an 
authority  on  chlorination,  is  as  follows  :* 

When  gold  assays  are  required  to  be  made  in  pyrites  or  mattes  which 
contain  less  than  11  per  cent,  of  silver,  the  quantites  of  ore  or  matte 
taken  for  the  assay  should  be  regulated  by  their  percentage  of  silver, 
thus  :  of  material  containing 

8.5  per  cent,  of  silver  take     48  blowpipe  centners. 

5.5         „  „  72 

2-5         „  „  144 

1-5         „  „  288 

But,  for  the   sake   of  rapidity,  50  to   100  grammes  of  the  finely  pul- 
verised substance,  weighed  011  a  less  delicate  balance,   is  roasted  in  a 
*  Translation  by  Mr.  D.  A.  Louis.     . 


90  Remedies. 

simple  manner  ;  the  gold  is  then  converted  into  chloride  by  means  of 
chlorine  gas,  extracted  with  water,  precipitated  in  the  metallic  state, 
and  further  treated  with  the  blowpipe.  The  method  employed  is  as 
follows  : 

The  weighed  substance  is  placed  on  a  sheet-iron  plate  which  has  been 
washed  over  a  few  times  with  fireclay  and  water,  and  dried,  and  more- 
over has  its  edges  turned  up.  This  is  heated  to  moderately  strong  red 
heat  over  a  charcoal  or  coke  fire  in  a  portable  furnace,*  under  a 
chimney  with  a  good  draught,  the  ore  is  stirred  with  an  iron  spatula 
and  the  heating  is  continued  until  the  odour  of  sulphurous  acid  ceases- 
to  be  detected.  When  cold  the  roasted  mass  is  rubbed  in  an  iron  mortar^ 
and  again  heated  to  redness,  on  the  iron  plate,  until  all  evidence  of 
sulphurous  acid  has  entirely  disappeared.  When  cool,  the  roasted  ore 
is  just  moistened  with  water,  in  a  porcelain  dish  or  spoon,  so  as  to  leave 
it  in  a  loose,  or  so-called  woolly  condition  when  stirred  with  a  rod  or 
rubbed  with  the  hands ;  this  condition  being  the  best  for  the  treatment 
with  chlorine.  If  the  roasting  has  been  quite  complete,  then  the  gold 
present  as  metal  may  be  converted  into  chloride  and  extracted  by  means 
of  freshly  prepared  chlorine  water  free  from  hydrochloric  acid.  If, 
however,  the  roasted  substance  still  contains  small  quantities  of  metallic 
sulphides  and  arsenides,  gaseous  chlorine  will  be  found  more  suitable,, 
and  by  taking  into  consideration  the  following  conditions,  the  gold  may 
be  completely  extracted.  1 .  The  substance  must  be  as  free  as  possible  from 
metallic  iron  (for  example,  particles  from  the  stamp-heads),  which  must 
be  sought  for  and  removed  by  a  magnet.  2.  The  roasting  should  be  care- 
fully conducted,  so  as  to  leave  as  small  a  quantity  of  undecomposed 
sulphides  and  arsenides  as  possible.  3.  The  chlorine  employed  must  be- 
absolutely  free  from  hydrochloric  acid,  which  not  only  dissolves  the- 
metallic  oxides  present,  but  also,  in  the  presence  of  an  iron  sulphide, 
gives  rise  to  sulphuretted  hydrogen,  and  the  latter  decomposes  gold 
chloride  already  formed,  precipitating  it  as  a  sulphide,  and  also  absorbs- 
the  chlorine,  so  that  very  little  gold  would  be  extracted.  The  chlorine- 
is  therefore  passed  through  water  to  remove  the  hydrochloric  acid,, 
and  the  extraction  proceeds  as  follows  : 

A  glass  cylinder  A,  200  mm.  to  250  mm.  high  and  60  mm.  in  dia- 
meter, with  a  neck  at  the  side  and  near  the  bottom  18  mm.  to  20  mm.  in 
diameter,  is  filled  to  above  the  neck  with  small  fragments  of  quartz,. 

*  Failing  a  suitable  portable  furnace  a  large  graphite  crucible  about 
0.3  metre  high,  such  as  used  for  fusing  metals,  is  employed ;  this  is 
pierced  at  one  side  near  the  bottom  by  a  hole  7  centimetres  square,, 
whilst  several  small  holes  are  cut  around  the  upper  edge,  and  a  suitable 
iron  grate  is  fixed  within  the  crucible. 


Remedies. 


91 


upon  which  is  spread  a  thin  layer  of  coarse  quartz  sand,  and  then  a 
layer  of  fine  sand,  so  as  to  form  a  filter.  The  moistened  roasted  ore  or 
matte  is  placed  upon  this,  so  as  to  lie  as  loosely  as  possible ;  the  top  of 
the  cylinder  is  then  closed  with  thin  sheet  india-rubber  previously 
warmed,  through  which  passes  the  tube  bent  twice  at  right  angles 
(it  is  best  to  use  two  tubes  connected  by  india-rubber  instead  of  one 
bent  tube) ;  and  dipping  into  cylinder  B  containing  a  roll  of  stiff  blotting 
paper  subsequently  moistened  with  spirit.  To  prepare  the  chlorine  re- 
quired for  200  grammes  of  roasted  ore,  10  grammes  of  finely  powdered 
manganic  oxide,  40  grammes  of  ordinary  hydrochloric  acid,  and 
10  grammes  of  sulphuric  acid  previously  diluted  with  an  equal  quantity 
of  water,  are  placed  in  the  flask  C,  and  after  mixing  well  by  whirling,, 
the  flask  is  placed  on  a  sand  bath,  heated  with  a  spirit-lamp,  and  connected 
in  the  ordinary  manner  by  means  of  a  cork  and  bent  tube  with  the  wash- 
bottle  D,  which  consists  of  a  wide-mouthed  bottle  more  than  half  filled 
with  water  and  closed  with  a  cork.*  From  this  bottle  the  chlorine 


fig.  1. 

passes  through  the  other  bent  tube  to  the  cylinder  A,  leaving  the 
hydrochloric  acid  dissolved  in  the  water  in  D.  If  the  apparatus  is  air- 
tight throughout  and  the  last  tube  reaches  to  nearly  the  bottom  of  B, 
then  the  extraction  of  the  gold  may  be  conducted  in  the  ordinary 
workroom  without  any  odour  of  chlorine  being  observed,  inasmuch  a& 
any  excess  of  that  gas  is  converted  into  chloral  and  hydrochloric  acid 
by  the  spirit  in  the  blotting-paper,  which  products,  as  is  known,  have 
properties  differing  from  those  of  chlorine.  The  flask  is  heated,  at 
first  very  slightly,  in  order  not  to  produce  too  vigorous  an  evolution  of 
gas,  but  afterwards  somewhat  stronger,  so  as  to  permit  the  chlorine 
*  If  any  chlorine  water  is  available  this  may  be  used,  inasmuch  as- 
at  the  beginning  pure  water  becomes  first  of  all  saturated  with  chlorine 
when  the  gas  is  allowed  to  bubble  into  it. 


$2  Remedies. 

evolved  to  be  thoroughly  washed  by  the  water  in  D.  The  absorption 
of  the  chlorine  in  A  and  ultimate  accumulation  in  the  upper  empty 
part  of  the  cylinder  and  its  passage  over  into  B  can  be  distinctly  seen, 
and  when  a  marked  quantity  of  gold  is  present  in  the  ore  or  matte,  the 
mass  undergoes  a  visible  change.  The  smaller  the  quantity  of  unde- 
composed  sulphides  and  arsenides  present  the  quicker  will  the  chlorine 
appear  at  the  top  of  cylinder  A,  and  the  larger  the  quantities  of 
impurities  present  the  slower  will  the  mass  be  penetrated,  and  there  will 
be  a  distinct  evolution  of  heat  in  the  glass  cylinder.  Although  all  the 
finely  divided  particles  of  free  metallic  gold  are  converted  into  chloride 
when  the  chlorine  appears  in  the  empty  part  of  the  cylinder, 
this  is  by  no  means  the  case  with  the  gold  attached  to  the  par- 
ticles of  sulphides  and  arsenides.  Therefore,  the  chlorine  must  be 
.allowed  to  pass  through  the  moistened  mass  for  at  least  an  hour,  before 
the  extraction  can  be  regarded  as  complete  and  the  apparatus  may  be 
aken  apart  (which  operation  is  of  course  started  by  removing  the  cork 
of  the  flask  C,  so  as  to  prevent  water  running  back  on  the  removal  of 
the  spirit-lamp). 

When  the  apparatus  is  disconnected  cylinder  A  is  placed  on  a  stand 
of  sufficient  height,  the  neck  at  the  bottom  is  closed  with  a  cork  through 
which  passes  a  piece  of  short  narrow  glass  tubing  (a  glass  tap  is  very 
convenient),  a  beaker  is  placed  under  this,  and  by  pouring  on  small 
quantities  of  hot  water  at  a  time,  the  gold  chlorides  and  any  other 
soluble  chlorides  which  may  perhaps  have  been  formed  are  washed  out, 
taking  care  to  tilt  the  cylinder  so  as  to  leave  no  solution  at  the  bottom.* 
The  liquid  is  first  treated  with  hydrochloric  acid  and  then  with  a  suffi- 
cient quantity  of  ferrous  sulphate  to  precipitate  all  the  gold  in  the 
metallic  state,  it  is  then  stirred  vigorously  with  a  glass  rod  and  allowed 
to  stand  until  the  gold  has  settled  down,  which  occurs  in  a  short  time 
when  the  liquid  is  kept  warm.  The  precipitated  gold  is  collected  on  a 
filter,  washed  with  water,  and  dried  with  the  filter  in  a  porcelain  dish  over 
the  flame  of  a  lamp.  When  dry  it  is  burnt  in  a  platinum  capsule  over 
the  spirit  lamp,  with  access  of  air,  and  is  mixed  directly  in  the  capsule 
with  one  to  two  blowpipe  centners  of  assay  lead  and  a  little  borax 
glass.  The  whole  mixture  is  wrapped  up  in  a  soda  paper  cylinder  and 
fused  on  charcoal  or  in  a  charcoal  crucible,  using  a  reducing  flame  as  in 
a  quantitative  silver  assay.  The  auriferous  lead  is  cupelled  011  a  bone- 
ash  cupel  and  the  gold  button  which  remains  is  either  weighed  on  the 
balance,  or  if  too  small  for  weighing  its  weight  is  estimated  by  measure- 

*  If  the  neck  is  placed  too  high  above  the  bottom  of  the  cylinder  the 
space  below  it  may  be  filled  with  molten  pitch  before  putting  in  the 
•quartz  fragments. 


Remedies.  93" 

ment  on  the  scale.*  As  a  rule  the  gold  produced  by  this  method  is  free 
from  silver,  inasmuch  as  the  silver  chloride  produced  during  the  treat- 
ment of  the  roasted  substance  is  insoluble  in  water.  If,  however,  the 
substance  has  not  been  well  roasted  so  that  moderate  quantities  of  other 
chlorides  could  form,  then  on  washing  the  powder  with  water  after  treat- 
ment with  chlorine  gas,  at  first  a  concentrated  solution  of  these  chlorides 
is  produced  in  which  the  chloride  of  silver  formed  is  not  wholly  insoluble, 
consequently  chloride  of  silver  will  pass  into  the  solution,  and  this,  in 
spite  of  the  liquid  becoming  more  and  more  diluted  with  water,  only 
separates  completely  with  extreme  slowness.  In  this  case  the  gold 
obtained  might  contain  a  little  silver,  and  must  therefore  be  subjected 
to  a  special  parting,  f 

*  If  200  grammes  of  ore  have  been  employed  in  the  assay,  which 
makes  200  x  10  =  2000  blowpipe  assay  centners,  then  it  is  only  necessary 
to  divide  the  weight  of  the  gold  obtained  in  the  balance,  or  by  the  scaley 
by  2000,  in  order  to  ascertain  the  percentage  in  the  ore  examined. 

f  It  is  scarcely  necessary  for  me  to  mention  that  the  method  described 
may  be  used  for  the  extraction  of  gold  on  a  large  scale  from  ores  which 
contain  it,  mineralized,  or  in  an  extremely  finely  divided  metallic  state ; 
nevertheless  it  may  not  be  wholly  without  interest  to  remark,  that 
for  this  purpose  cylindrical  wooden  extraction  apparatus  may  be 
employed  which  narrow  internally,  so  that  their  lower  ends  form  in- 
verted pyramids,  and  the  internal  surface  being  covered  with  asphalt. 
For  the  purification  of  the  chlorine  in  the  washing  apparatus  the 
gas  may  pass  into  the  wash-water  through  a  porcelain  tube,  the  end  of 
which  is  a  large  hollow  ball  pierced  with  a  considerable  number  of 
small  holes,  so  that  every  trace  of  hydrochloric  acid  will  be  held  back. 

When  leaving  the  records  of  the  early  investigators 
and  workers,  and  before  plunging  into  the  maze  of 
patents,  which,  in  more  recent  years,  cover  the  self- 
same ground,  it  may  be  well  to  make  a  few  general 
remarks  on  the  subject  of  chlorination,  although  the 
records  which  follow  are  not  entirely  confined  to  this 
method  of  dissolving  gold. 

Chlorine  being  the  active  dissolving  element  in  the 
method  now  under  discussion,  it  has  for  years  been 
known  by  the  name  "  chlorination;"  since  the  time 
that  Guettler  first  applied  the  process  it  has  been 


94  Remedies. 

widely    adopted,     and     most     of    those    who     followed 
the  steps  of  the  early  investigators  already  mentioned 
claimed  to  be  the  originators  of  further  "  inventions."    It 
will  be  seen  that  none  of  these  gentlemen  have,  in  this 
connection,  invented  anything  in  the   way  of  chemical 
reactions,  excepting  perhaps  certain  difficulties.      Nature 
was  the  first  chlorinator,   and  the  adapter   who  follows 
the    procedure   of  nature    cannot    fail   to    be   successful. 
Judged    by   the    measure    of    our    short    span    of    life, 
nature  works  slowly ;  any  inventor  fortunate  enough  to 
devise  means  of  accelerating  her  actions  does  well .;  but  it 
is  doubtful  whether  any  will  succeed  in  improving  natural 
laws,    which    some    appear    to    have    attempted.       The 
"Plattner,"  and  all  other  kindred  methods,  have  failed 
over  and  over  again,  almost  entirely,  by  reason  of  want 
of  knowledge  on  the  part  of  the  operator.     Frequently 
failure  results  from  chlorination  being  applied  to  unsuit- 
able ores,  but  in  this  sense  failure  can  only  be  considered 
from  a  financial  point  of  view,  when  judged  relatively  by 
the  results  of  other  methods. 

Whenever  the  hitherto  unsolved  problem  of  producing 
artificially  the  same  reactions  as  in  natural  decomposi- 
tion, or  of  starting  these  actions,  which,  once  begun,  are 
comparatively  rapid,  the  complex  questions  involved  in 
the  treatment  of  gold-bearing  pyritous  ores  will  be  made 
simple,  for  then  there  will  be  no  need  of  any  process, 
save  that  of  dissolving  the  gold  and  precipitating  it  from 
its  solutions,  when  too  fine  to  save  by  gravitation 
methods ;  but  as  it  is  necessary  to  deal  with  what  is, 
not  what  may  be,  a  few  remarks  on  the  methods  of 
roasting  effectively  should  be  appended,  as  roasting  or 
other  decomposition  is  the  primary  essential  step  in  the 
process. 


Remedies.  95 

For  purposes  of  clearness  it  may  be  well  to  here 
reiterate,  in  brief,  the  natural  reactions  already  referred 
to.  Decomposition  of  the  gold-bearing  minerals,  dis- 
solving of  the  gold  therein,  filtration  of  the  solution  from 
the  residue,  precipitation  of  the  gold  ;  which  reactions 
are  brought  about  in  this  way  :  the  natural  saline  waters 
in  conjunction  with  air  supply  oxygen  to  decompose  the 
pyrites  ;  sulphuric  acid,  one  of  the  resultants,  acts  on  the 
natural  saline  waters  and  forms  hydrochloric  acid  ;  this 
coming  into  contact  with  manganese,  or  other  oxidizing 
agent,  liberates  the  solvent  for  gold ;  the  gold  dissolved 
and  solution  is  carried  with  the  water  which  percolates 
through  rocks,  &c.,  and  by  such  natural  filtration  the 
liquid  is  separated  from  solids ;  lastly,  precipitation  of 
the  gold  from  solutions  is  brought  about  by  many  natural 
though  more  or  less  complex  reactions. 

To  copy  as  closely  as  possible  nature's  course,  the 
chemists  and  experimenters,  in  the  years  1846-9,  saw 
that  decomposition  of  the  pyrites  was  the  first  necessity, 
and  calcination  or  roasting  in  the  presence  of  atmo- 
spheric air  was  the  means  chosen  to  bring  about  rapid 
oxidation.  This  roasting  process  is  the  only  one  in 
vogue  even  to  the  present  day,  but  it  is  a  most  unsatis- 
factory imitation  of  natural  oxidation  and  the  beautiful 
reactions  which  follow,  for  could  natural  decomposition 
be  followed  or  hastened,  everything  could  be  put  into 
solution  in  the  manner  of  nature,  and  then  from  this 
solution  the  same  chemically  accurate  separations  could 
be  made.  Roasting  produces  oxidation,  the  first  step  in 
natural  decomposition,  but  by  driving  away  many  con- 
stituents of  the  ore  destroys  all  possibility  of  following 
closely  the  other  reactions,  therefore  the  chemicals 
necessary  to  bring  about  the  solvent  solutions  must  be 


96  Remedies. 

introduced.  For  this  purpose  roasted  ore  is  placed  in  a 
vat,  and  chlorine  gas,  made  in  a  separate  vessel,  is  passed 
into  it ;  after  this  gas  has  transformed  the  gold  into 
chloride  (Au  C13),  the  chloride  is  dissolved  by  water  and 
carried  out  of  the  ore  by  filtration  or  straining — in 
a  similar  manner  as  when  the  gold  solutions  are  moved 
by  the  natural  action  of  water ;  precipitation  of  the  gold 
is  brought  about  by  adding  sulphate  of  iron  or  other 
precipitant — sulphate  of  iron  is  also  a  natural  product  of 
decomposing  pyrites — and  the  metal  is  collected  from 
the  bottom  of  settling  vats,  where  it  falls  as  a  finely 
divided  brown  powder. 

ROASTING. 

So  far  no  satisfactory  form  of  furnace  has  yet  been 
devised  for  the  successful  roasting  of  pyritous  ores. 
When  dealing  with  the  subject  in  several  of  the  Govern- 
ment reports,  Mines  Department,  Victoria,  Mr.  Newbery 
has  stated  that  a  grain  of  pyrites  when  put  under  the 
oxidizing  flame  of  a  blowpipe,  may  be  perfectly  calcined 
in  less  than  one  minute,  whereas  if  a  quantity  of  the 
same  pyrites,  reduced  to  similar  sizes,  be  put  in  any  of 
the  ordinary  calcining  furnaces,  from  eight  to  fourteen 
hours'  exposure  there  is  necessary  to  bring  about  the 
same  result ;  this  illustration  has  been  appropriated  by 
an  American  writer  without  acknowledgment. 

The  difference  in  these  results  is  entirely  a  question  of 
air  supply,  and  apparently  the  point  overlooked  by  most 
furnace  constructors  is,  that  the  sulphur  in  pyrites  will 
not  burn  or  oxidize  in  an  atmosphere  charged  with 
sulphurous  acid  ;  the  percentage  is  a  varying  quantity 
with  temperature,  but  in  all  cases  may  be  considered 
very  low,  somewhere  about  15  per  cent.  As  a  candle 


Remedies.  97 

flame  is  put  out  by  carbonic  acid  gas,  the  product  of  its 
own  combustion,  so  is  pyrites  extinguished  by  sulphu- 
rous acid,  the  product  of  burning  sulphur,  the  combustible 
portion  of  this  mineral.  Although  the  metallurgist 
appears  to  have  overlooked  this  fact,  the  action  is  known 
to  the  old  housewife,  as  may  be  judged  by  her  common 
practice  of  throwing  sulphur  on  a  fire  to  extinguish  a  burn- 
ing chimney  ;  sulphurous  acid  being  produced,  yielding  an 
atmosphere  in  which  no  combustion  can  be  sustained. 

Perfect  roasting  is  a  preparatory  essential  to  success  with 
either  the  amalgamation  or  chlorination  of  complex  ores. 
The  supply  of  pure  air  is  the  key  to  the  whole  question; 
and  when  a  correct  furnace  is  devised,  wherein  the  mass 
intended  to  be  calcined  has  not  for  hours  to  stew  in  its 
own  juice,  hundreds  of  tons  of  pyrites  may  be  roasted 
with  the  same  amount  of  heat  now  wasted  in  the  treat- 
ment  of  one  ton.* 

For  the  successful  extraction  of  gold  from  pyritous 
ores  the  iron  must  be  converted  by  roasting  into  a  soft 
ferric  oxide,  and  the  attainment  of  this  result  depends 
not  only  on  the  construction  of  the  furnace  but  also  on 
the  skill  shown  in  manipulation.  Any  ore  given  a  full 
supply  of  air,  and  kept  at  a  proper  temperature  for  a 
sufficient  time,  according  to  its  requirements,  will  be 
properly  and  perfectly  calcined,  but  if  the  necessary 
conditions  are  not  correctly  observed,  in  the  same 
ratio  as  the  ores  treated  are  complex,  so  will  imperfect 
results  increase. 

To  enter  fully  into  the  complex  questions  met,  when 
dealing  with  the  subject  of  roasting  ores,  would  necessi- 
tate another  volume  quite  as  large  as  the  present,  but, 

*  Any  one  doubting  this  statement  may  with  advantage  study  the 
reactions  in  Hollway's  copper  process. 


H 


98  Remedies. 

for  purposes  of  illustrations,  a  few  simple  cases  may  be 
cited.  The  much-talked- of  loss  in  roasting  by  volati- 
lization or  "going  up  the  chimney"  is,  with  oxidizing 
roasting,  a  myth,  and  exists  only  in  some  lively  imagina- 
tions ;  the  loss,  if  any,  is  very  small,  for  the  temperature 
in  furnaces  is  never  raised  to  anything  like  that  which  the 
gold  in  melting  pots  is  subject  to.  At  the  Melbourne 
mint,  where  gold  to  the  value  of  nearly  three  millions 
sterling  is  melted  every  year,  the  loss  by  volatilization  is 
estimated  to  be  under  30/.  annually.  When  roasting 
clean  iron  pyrites  the  commonest  form  of  trouble  is  the 
formation  of  magnetic  oxide  of  iron,  the  pyrites  grains 
contract  and  become  intensely  hard  ;  the  gold  contained 
is  locked  up  in  a  sort  of  slag,  from  which  removal  is 
almost  an  impossibility.  If,  when  the  charge  is  delivered 
from  the  furnace,  it  presents  a  black  appearance,  from 
the  foregoing  cause  difficulties  may  without  fail  be 
anticipated,  either  in  chlorination  or  amalgamation. 
Few  deposits  of  pyrites  are  without  some  galena ;  when 
in  the  furnace  this  produces  oxide  and  sulphate  of  lead, 
the  reducing  gases  and  carbonaceous  matter  from  the 
fire  frequently  transform  the  oxide  into  the  metallic  lead, 
and  the  oxide  and  sulphate  reacting  upon  each  other 
also  bring  about  this  result.  This  metallic  lead  amal- 
gamates with  or  takes  up  gold,  and  as  air  is  also  present, 
the  metallic  globules  or  particles  in  turn  become  coated 
with  oxide  (litharge),  which  melts  very  easily  and 
absorbs  sand  grains,  and  so  particles  containing  gold  are 
formed  which  reject  either  an  amalgamating  or  a  dissolv- 
ing medium.  Antimony  acts  in  a  similar  manner.  Car- 
bonaceous matter  also  makes  from  arsenious  acid  metallic 
arsenic,  the  fumes  of  which  are  readily  absorbed  by 
heated  gold;  the  gold  becomes  quite  brittle,  is  easily 


Remedies.  99 

broken  up,  and  cannot  afterwards  be  treated  satisfactorily 
by  amalgamation. 

The  following  will  illustrate  how  gold  so  affected  soon 
becomes  non-recognisable,  even  by  those  who  work  and 
deal  in  it  every  day.  Some  years  ago,  in  Victoria,  a 
great  deal  of  swindling  was  practised  on  the  goldfields, 
when  articles  were  purchased  from  storekeepers  with 
gold  dust,  or  when,  before  the  advent  of  banks,  they 
were  the  gold  buyers  or  medium  for  its  transference  to 
cities.  Some  miners  used  to  mix  with  gold  dust,  brass 
filings,  particles  of  gilded  lead,  or  any  substance  which 
would  make  up  weight  and  escape  detection.  The 
simple-minded  Chinamen,  as  is  their  wont,  rapidly  picked 
up  the  devious  way  of  the  European  diggers,  and  soon 
became  so  expert  as  to  completely  out-do  them  in  this 
branch  of  industry  ;  in  fact,  "  took  the  bread  out  of  their 
mouths."  The  Chinese  were  never  popular,  and  this 
faculty  of  imitation  did  not  tend  to  improve  the  general 
feeling  towards  them ;  and  soon  a  loud  outcry  was 
raised  against  "  their  ways  which  were  dark,  and  tricks 
that  were  vain,"  and  every  one  "  laid  themselves  out "  to 
catch  the  heathen.  At  S  taw  ell,  where  kiln  roasting  of 
arsenical  ore.s  had  been  carried  on,  some  Chinamen  were 
fossicking  amongst  the  rubbish  in  disused  kilns  and  came 
upon  a  lot  of  heavy  stuff,  which  they  pronounced  to  be 
gold.  One  of  these  fellows  brought  this  stuff  for  sale  to 
a  storekeeper.  Here  was  the  long-looked-for  chance  : 
the  unfortunate  wretch  was  pounced  upon,  generally 
maltreated,  and  packed  off  to  Melbourne — 200  miles 
distant — to  await  his  trial  for  a  heinous  offence.  He 
was  arraigned  before  all  the  pomp  and  majesty  of  the 
law,  and  learned  men  were  there  in  force  to  testify  to 
his  guilt.  During  the  course  of  the  trial,  one  of  the 


100  Remedies. 

detectives — with  more  than  the  ordinary  forethought  of 
his  class — bethought  himself  to  submit  to  the  Chief  of 
the  Technological  Museum  some  of  this  grey-looking 
stuff,  which  could  be  broken  like  a  biscuit,  for  an  opinion 
as  to  what  it  really  was.  As  soon  as  Mr.  Newbery  saw 
it,  he  at  once  pronounced  it  to  be  an  alloy  of  gold  and 
arsenic  ;  this  was  in  a  few  minutes  verified  when  the 
stuff  was  put  in  a  cupel  furnace,  from  which  it  appeared 
as  a  bright  yellow  metallic  gold. 

In  Mr.  R  Brough  Smyth's  "  Gold  Fields  of  Victoria," 
Mr.  J.  Cosmo  Newbery 's  notes  on  this  point  are  given  ; 
the  extracts  are  as  follows  : 

Native  arsenic  has  not  been  found  in  the  ores  of  the  goldfields  of 
Victoria,  but  this  substance  occurs  largely  in  combination  with  iron  and 
sulphur,  in  arsenical  pyrites,  also  as  arseniates  of  lead,  copper,  and  iron. 
From  any  of  these  minerals  it  may  be  easily  set  free  in  the  roasting 
furnace  and  quartz-kilns,  especially  the  latter,  owing  to  the  fuel  and 
reducing  gases  produced  by  the  imperfect  combination  coming  into 
contact  with  these  ores.  When  arsenic  is  thus  set  free,  it  passes 
through  the  furnace  as  a  vapour,  and  is  readily  taken  up  by  the  gold 
that  may  be  present;  for,  when  gold  is  heated  to  redness,  or  any 
degree  between  that  and  its  melting  point,  it  takes  up  arsenic,  with 
which  it  forms  a  grey,  easily  fusible,  brittle  alloy  ;  even  when  the 
arsenic  is  not  in  sufficient  quantity  to  change  the  colour  of  the  gold, 
or  its  fusing  point,  it  still  renders  it  very  brittle — one-thousandth  part 
renders  gold  so  brittle  that  it  may  be  ground  to  powder 

Metallic  antimony  has  a  great  affinity  for  gold  ;  it  forms  an  alloy, 
both  when  the  two  metals  are  melted  together,  or  when  the  vapour  of 
antimony  is  passed  over  heated  gold.  The  alloy  produced  is  grey  in 
colour  and  very  brittle,  and  amalgamates  with  mercury  only  after  a 
long  contact  and  continual  grinding,  or  by  heating  the  two  together. 
The  amalgam,  when  formed,  floats  on  mercury,  and  gradually  gives  up 
metallic  antimony  as  a  fine  powder  when  agitated  with  water.  This 
antimonial  powder  carries  off  a  quantity  of  mercury  and  gold  amalgam 
entangled  with  it. 

Some  writers  recommend  the  addition  of  salt,  or 
chloridizing  roasting,  when  dealing  with  certain  ores. 


Remedies.  101 

Mr.  Stetefeldt,  who  is  a  high  authority  on  the  subject, 
writes  as  follows:^ 

The  percentage  of  gold  extracted  by  amalgamation  decreases  with 
the  increase  of  the  temperature  at  which  roasting  is  conducted,  and 
with  the  time  consumed  in  roasting,  or  the  time  during  which  the 
charge  is  kept  red-hot  after  being  withdrawn  from  the  roasting  furnace. 
If  we  inquire  in  what  condition  the  gold  is  found  in  roasted  ore,  and 
especially  why  it  does  not  amalgamate  to  a  higher  percentage,  we  may 
just  as  well  confess  we  do  not  know.  There  is  a  monochloride  of  gold 
(Au  01)  which  has  some  stability  above  a  temperature  of  185  deg.  C.,  at 
which  the  ter-chloride  decomposes,  and  which,  as  a  sodium  double  salt, 
is  said  to  exist  at  a  dark  red  heat,  according  to  Plattner  and  Kiss.  We 
know  that  monochloride  of  gold  is  insoluble  in  water,  and  the  sodium 
double  salts  formed  in  roasting  may  share  the  same  property.  It  is 
further  asserted  that  this  monochloride  of  gold  is  not  decomposed  by 
quicksilver,  but  I  cannot  find  a  record  of  any  experiment  to  prove  this 
fact.  Finally,  we  know  that  monochloride  of  gold  is  soluble  in  sodium 
and  hyposulphite  solutions,  while  metallic  gold  is  little  affected  by 
sodium  hyposulphite.  According  to  the  above  statements  the  gold 
present  as  a  monochloride  would  be  lost  in  amalgamation,  but  extracted 
by  lixiviation  with  a  hyposulphite  solution. 

PATENTS,  &c. 

Investigators  who  are  anxious  to  know  what  has  been 
done  by  patentees  of  solvent  processes  may  prepare  them- 
selves for  the  reading  of  a  mass  of  overlapping,  and 
more  or  less  unintelligible,  claims,  created  by  the  fertile 
minds  of  "  inventors ;"  only  a  few  of  the  specifications  are 
at  all  clearly  drawn,  or  appear  to  take  any  note  of  what 
has  been  previously  claimed. 

SPICKER,  1852. 

The  first  patentee  on  the  subject  appears  to  be  Charles 
Spicker,  who  on  the  10th  of  February,  1852,  took  out  a 
patent  in  the  United  States,  No.  8729,  for  "  Improve- 
ments in  Process  .for  Dissolving  Gold,"  the  abstract  for 
the  same  in  the  Official  Gazette  being  as  follows  : 

*  Trans.  Am.  Inst.  Min.  Eng.,  vol.  xiii. 


102  Remedies. 

What  1  claim  now  as  my  invention,  and  desire  to  secure  by  letters 
patent,  is  the  separating  of  gold  from  its  ores,  sands,  or  mixtures,  in 
suitable  apparatus  by  the  use  of  free  chlorine  gas,  when  absorbed  by 
water  alone,  or  by  water  in  combination  with  an  alkali  or  an  alkaline 
earthy  or  metallic  chloride,  containing  an  excess  of  chlorine,  as  set 
forth  in  the  specification. 

Unfortunately,  the  early  specifications  of  the  United 
States  patents  are  not  obtainable  in  the  London  Patent 
Office,  abstracts  alone  being  given,  and,  as  the  above  is 
all  the  information  available,  criticism  of  the  claims  are 
precluded. 

PRIMARD,  1857. 

The  next  patentee  on  the  subject  appears  to  be  Edouard 
Primard,  civil  engineer,  Paris,  whose  patent  for  Great 
Britain,  No.  1931,  is  dated  llth  July,  1857;  (this  patent  is 
referred  to  in  Dingier,  Bd.  149,  page  77).  The  early 
portion  of  the  specification  relates  to  the  details  of  what 
would  now  be  considered  a  most  peculiar  stamper  bat- 
tery ;  a  kiln  is  also  described ;  the  matter  then  runs  : 

In  order,  however,  to  cause  the  quartz  to  be  more  easily  pulverised,  I 
begin  by  submitting  the  same  to  an  elevated  temperature  in  a  closed 
kiln,  so  as  to  prevent  any  undue  evaporation  of  the  metals,  and  the 
quartz  having  been  thus  brought  to  the  required  degree  of  heat,  I  cause 
a  small  stream  of  water  to  be  projected  on  the  same 

The  portion  referring  to  chlorination  runs  as  follows  : 

The  quartz  and  the  shistus  or  other  earths  having  thus  been  reduced, 
together  or  separately,  to  an  almost  impalpable  powder,  are  now  sub- 
mitted to  the  action  of  chlorine  gas  in  the  apparatus  represented  in  the 
Figs.  2,  3.  The  same  consists  of  a  retort  a  in  which  chlorine  is  evolved 
by  any  of  the  known  means,  and  carried  by  the  pipe  b  into  the  receiver 
c,  the  interior  of  which  is  lined  with  lead,  and  furnished  with  a  perfo- 
rated false  bottom  d,  on  which  the  powder  after  having  been  mixed 
with  a  sufficient  quantity  of  boiling  water  is  spread  out.  The  pipe  b 
opens  in  the  false  bottom  d,  in  order  to  cause  the  chlorine  gas  to  pass 
through  the  ore  spread  out  on  the  said  false  bottom,  from  where  the  gas 
is  conducted  by  another  pipe  51,  opening  in  a  similar  manner  in  the 
false  bottom  of  a  second  receiver,  from  where  another  pipe  carries  the 


Remedies. 


103 


gas  to  a  third  receiver,  and  so  on  for  a  sufficient  number  of  receivers 
which,  if  required,  may  be  placed  all  round  the  retort  a.  Each  of  the 
receivers  is  furnished  at  the  top  with  a  hole  for  introducing  and  with- 
drawing the  crushed  ore,  which  hole  is  hermetically  closed  up  during 
the  introduction  of  the  gas  in  the  receiver ;  at  the  bottom  each  receiver 
has  a  pipe  e  with  stopcock  for  drawing  off  the  water  collected  below  the 
false  bottom.  The  crushed  ore,  before  being  introduced  in  the  receivers, 
is  mixed  with  a  sufficient  quantity  of  boiling  water,  so  as  to  obtain  a 
temperature  of  from  20  deg.  to  30  deg.  C.  In  each  receiver  a  layer  of 
quartz  and  sand  is  introduced  between  the  false  and  the  real  bottom,  so 
as  to  serve  as  a  filtering  medium.  The  chlorine  having  acted  on  the 
ore  sufficiently  long  to  effect  the  transformation  of  the  gold  into  chlo- 
ride, the  same  is  washed  with  hot  water,  which  water  being  collected 


Pig.  2. 


f  Fig.3. 


the  gold  is  precipitated  therefrom  in  the  ordinary  manner  by  sulf- 
hydric  acid  or  any  other  suitable  means. 

The  ore  treated  in  this  manner  still  contains  the  silver,  which  latter 
is  extracted  by  the  following  means  : 

On  the  ore  in  each  of  the  receivers  c  is  laid  a  sufficient  quantity 
of  chloride  of  sodium  according  to  the  silver  contained  in  the  ore. 
The  receivers  are  then  connected  with  a  steam  boiler  or  generator  in 
the  manner  as  shown  in  Fig.  3,  in  which  figure  /  represents  the  steam 
boiler  from  which  a  main  pipe  g  conveys  the  steam  to  each  of  the 
receivers  c  c\  <fcc.,  by  means  of  dipping  pipes  h  h\  &c.  The  steam 
having  acted  in  this  manner  on  the  ore  for  about  two  hours,  the 
water  condensed  between  the  false  and  real  bottoms  is  drawn  off  by 
means  of  the  pipes  e ;  this  water  contains  the  silver,  which  latter  is 


104  Remedies. 

precipitated  therefrom,  and  the  pure   silver  further  obtained  from  this 
precipitate  by  any  suitable  means. 

Having  thus  described  and  particularly  ascertained  the  nature 
of  my  invention,  and  the  manner  in  which  the  same  is  or  may  be 
used  or  carried  into  effect,  I  claim  the  apparatuses  and  modes  of 
operating  hereinbefore  described,  in  as  far  as  they  are  to  be  em- 
ployed for  the  extracting  of  gold  and  silver  or  other  metals  from 
their  ores. 

Primard's  method  was  barrel  chlorination  (Duflos) 
without  the  advantage  to  be  gained  of  rotating  the 
charge  while  under  treatment ;  the  idea  of  adding 
trunnions  to  the  barrels  was  to  facilitate  their  being 
emptied.  When  erecting  chlorinating  works  in  Japan 
many  years  ago,  Mr.  E.  Riotte  followed  Mr.  Primard's 
principle,  but  substituted  semi-cone  shaped  vats  for  bar- 
rels. There  was  no  novelty  in  Mr.  Primard's  method  of 
silver  extraction,  for  with  the  exception  of  trifling  mecha- 
nical details  the  same  procedure  had  long  been  followed. 

DEETKEN,  1858. 

Although  Mr.  Deetken  did  not  take  out  a  patent  until 
1863,*  and  then  for  a  slightly  different  procedure  to  that 
described  below,  yet  according  to  Guido  Kustel — in  his 
work  on  chlorination,  published  in  San  Francisco  in  1868 
— chlorination  "  was  first  introduced  in  Nevada,  Cal.,  by 
Mr.  Deetken  in  1858."  Kustel  describes  very  minutely 
the  "  Plattner "  process,  which  he  states  Deetken  in- 
troduced. As  the  "  Plattner "  process,  described  by 
Kustel,  is  one  of  the  only  two  chlorine  processes  in 
general  adoption  to  the  present  day,  it  may  be  as  well  to 
extract  from  his  most  exhaustive  work,  which  is  generally 
regarded  as  one  of  the  only  standard  works  on  the  sub- 

*  It  is  probable  that  as  Kustel  did  not  write  until  1868,  Mr. 
Deetken's  plant  was  by  that  time  so  modified  as  to  be  similar  to  that 
shown  in  Kustel's  work. 


Remedies.  105 

ject.  The  following  excerpts  bear  directly  on  the  present 
investigation  : 

The  gold  must  always  be  in  a  metallic  state.  Quartz  free  from 
other  earths  and  sulphurets,  containing  very  fine  gold,  can  be  subjected 
to  chlorination  without  other  preparation  than  moistening  with  water, 
as  described  further  on.  Very  hard  quartz  causing  a  greater  wear  of 
shoes  and  dies  may  give  a  less  favourable  result,  on  account  of  the 
metallic  iron.  Sulphuretted  ore  requires  a  perfect  roasting.  The 
presence  of  lead  makes  a  careful  roasting  necessary,  commencing  with  a 
very  low  temperature.  All  metals,  except  gold,  must  be  transformed 
into  oxides.  Sulphates  are  injurious. 

The  chlorine  gas  must  be  free  from  muriatic  acid.  From  the 
generator  the  gas  is  forced  through  clear  water,  by  which  the  muriatic 
acid  is  absorbed.  The  muriatic  acid  dissolves  the  oxides  and  causes, 
when  sulphides  are  present  in  consequence  of  defective  roasting,  the 
formation  of  sulphuretted  hydrogen,  by  which  the  soluble  chloride  of 
gold  is  precipitated.  The  muriatic  acid  dissolves  also  oxides  of  metals, 
which  are  precipitated  by  the  addition  of  sulphate  of  iron  with  the  gold. 

The  roasting  is  the  most  important  part  of  the  whole 

operation — that  on  which  the  success  of  the  chlorination  principally  de- 
pends   The  roasted  ore  cannot  be  treated  at  once  with 

chlorine  gas,  for  two  reasons — -first,  because  the  sulphurets,  if  dry,  form 
a  more  condensed  mass  than  if  in  a  certain  damp  condition,  and  are 
therefore  more  obstructive  to  the  ascending  gas  ;  and  secondly,  for  the 
more  important  reason  that  the  chlorine  does  not  act  as  vigorously  on 
dry  as  on  damp  ore.  It  is  therefore  indispensable  to  moisten  the  sul- 
phurets* after  they  are  sufficiently  cool.  For  this  purpose  the  roasted 
charge  of  several  tons  is  spread  in  a  compartment  of  8  ft.  or  10  ft. 
square  with  sides  2  ft.  high  of  thin  boiler  iron,  and  the  water  conducted 
over  it  by  means  of  a  hose  or  otherwise.  It  may  require  from  4  to  5 
per  cent,  of  water.  The  wetted  surface  is  then  turned  over  several  times 
and  mixed  with  the  dry  stuff  beneath  till  it  appears  nearly  uniform.  The 
moistened  charge  must  riot  create  the  slightest  dust,  but  at  the  same 
time  the  hand  should  remain  dry  and  clear  on  handling  it.  A  handful 
of  it  pressed  hard  together  must  form  a  lump  which  can  be  held  in  the 
fingers,  but  falls  into  its  former  loose  condition  if  handled.  Should  it 
appear  too  dry  some  more  water,  or  in  the  reverse  case,  some  more  dry 
ore,  must  be  added  and  mixed  with  it.  Further  on  it  will  be  seen  that 

*  When  Mr.  Kustel  refers  to  sulphurets  in  this  description  he 
evidently  means  roasted  ore  ;  no  longer  sulphurets,  but  a  mixture  of 
oxides. 


106 


Hemedies. 


the  vats  in  which  the  chlorinatioii  is  performed  contain  a  false  bottom 
on  which  a  filter  is  prepared.  After  a  charge  has  been  removed  this- 
filter  contains  a  great  deal  of  moisture,  which  draws  into  the  newly- 
moistened  charge,  rendering  the  lowest  stratum  too  moist ;  whereby  it 
settles  somewhat  and  hinders  the  free  access  of  the  introduced  chlorine. 
To  avoid  this  some  dry  ore  is  spread  over  the  filter,  that  is,  the  bottom,, 
say  8  in.  or  10  in.  deep,  and  allowed  to  lie  for  six  or  eight  hours.  Should 
it  be  found  too  dry  or  too  wet  it  must  be  made  right  by  the  addition  of 
moistened  or  dry  stuff  as  the  case  may  be.  A  short  experience  will 
teach  one  to  introduce  the  proper  amount  of  roasted  ore  necessary  to> 
take  up  the  moisture.  This  charge  part  as  well  as  the  moistened,  as 
described  before,  must  be  subjected  to — 

Sifting.  This  operation  takes  but  a  short  time  and  is  necessary  for 
two  reasons.  One  is  the  separation  of  lumps  and  crusts  formed  during; 
the  roasting,  and  of  other  impurities  which  might  drop  in  accidentally,. 


all  amounting  to  2  or  3  per  cent.  The  other  reason  is  the  required 
loose  condition  of  the  ore  in  the  vat,  which  is  best  obtained  by  passing; 
it  through  a  sieve.  For  this  reason  the  sifting  must  be  performed 
directly  into  the  vat.  The  sieve  is  12  in.  to  14  in.  by  25  in.  in  the  clearr 
the  sides  5  in.  high.  The  sieve  is  sufficiently  fine  if  there  are  seven  to- 
eight  meshes  to  the  running  inch. 

A  chlorination  vat,  into  which  the  ore  is  sifted  by  pushing  the  sieve- 
to  and  fro,  either  on  two  scantlings  laid  over  the  rim  of  the  tub,  or 
suspended  on  four  ropes.  In  Fig.  4  is  represented  a  vertical  cross- 
section  of  a  circular  vat,  7  ft.  in  diameter,  capable  of  holding  3  tons  of 
roasted  sulphurets.  Above  the  bottom  b  is  an  empty  space  over  the 
whole  bottom  1  in.  high  formed  by  the  false  bottom  a,  the  boards  of 
which  are  laid  together,  leaving  about  J  in.  space  between  them. 
Besides  this  there  are  J  in.  holes  bored  in  it  from  10  in.  to  12  in.  apart. 
The  boards  are  supported  by  short  pieces  c,  leaving  sufficient  space  for 


Remedies. 


10T 


the  passage  of  the  chlorine.  Over  the  false  bottom  is  spread  first  a. 
layer  of  clear  quartz  from  1 J  in.  to  2  in.  in  thickness.  In  default  of 
quartz  another  kind  of  rock  will  answer  the  purpose  provided  there  is 
no  lime  or  talc  (sic)  in  it,  which  would  absorb  a  considerable  amount 
of  the  chlorine  ;  and  if  notice  is  not  taken  of  the  character  of  the  rock 
the  greater  consumption  of  chlorine  might  be  supposed  to  be  the  con- 
sequence of  defective  roasting.  Over  the  coarse  layer  smaller  pieces 
are  laid,  and  so  on,  decreasing  in  size  till  a  layer  of  sand  covers  the 
whole,  forming  thus  a  filter  of  from  4  in.  to  5  in.  in  thickness.  This 
filter  remains  always  in  the  vat;  the  shovelling  out  of  the  residue 
therefore  must  be  done  carefully  on  approaching  the  filter  bottom. 
There  are  two  holes  communicating  with  the  space  below  the  false 
bottom.  One  is  for  the  reception  of  the  lead  pipe  d,  by  which  the 
chlorine  is  introduced  ;  the  other  is  provided  with  a  leaden  cock  c,  for 
discharge  of  the  lixivium.  This  side  of  the  vat  stands  J  in.  lower. 


The  wooden  vat  would  absorb  a  great  quantity  of  the  gold  in  solution! 
if  the  inside  were  not  coated  with  some  material  which  prevents^  the 
soaking  in  of  the  fluid.  Mr.  Deetken  uses  one  part  pitch  melted  and 
one  part  of  tar.  This  is  a  cheap  and  quite  suitable  mixture,  and  is 
applied  by  means  of  a  brush  when  hot.  It  is  a  matter  of  course  also 
that  the  boards  of  the  false  bottom  should  be  coated  carefully  on  all 
sides,  as  well  as  the  whole  of  the  inside. 

There  are  also  vats  or  tubs  5  ft.  in  diameter  3  ft.  high,  holding 
two  tons  of  roasted  sulphurets.  Three  or  more  of  them  are  arranged 
in  one  row,  as  shown  by  Fig.  5.  They  are  conveniently  managed,  and 
preferred  where  small  charges  of  custom  ore  are  to  be  treated. 

Deetken  introduced  successfully  a  large  vat  of  10  ft.  diameter  2  ft. 
high,  constructed  exactly  like  Fig.  1.  This  vat  is  capable  of  holding 
from  6  to  7  tons  of  roasted  sulphurets.  The  usual  charge  is  6  tons. 


108 


Remedies. 


There  is  doubtless  more  economy  in  treating  6  tons  in  one  vessel  than 
in  two  or  three  of  a  smaller  size ;  there  is  less  waste  of  material  and 
some  saving  of  labour  with  the  larger  size. 

Chlorination  vats  with  a  greater  diameter  are  preferable  to  higher 
tubs  of  the  same  capacity ;  for  the  reason  that  a  low  column  of 
sulphurets  assumes  a  less  dense  condition,  and  also  because  of  the 
greater  cukic  contents  of  the  free  space  above  the  sulphurets  which 
is  filled  with  the  chlorine,  so  that  an  accidentally  greater  consump- 
tion of  the  gas  can  be  replaced. 

The  cover  g,  Fig.  4,  must  fit  as  well  as  possible  in  the  step  of  the 

6. 


vat  side,  but  not  too  tight ;  the  planks,  however,  have  to  be  fitted 
together  tightly  with  tongue  and  groove.  For  the  purpose  of  lifting 
there  are  generally  three  or  four  chains  fastened  to  the  cover.  Ropes 
are  of  no  use  as  they  are  destroyed  in  a  short  time  by  the  gases. 

The  moistened  ore,  as  before  said,  is  sifted  directly  into  the  vat  over 
the  filter.  In  order  to  avoid  a  condensed  charge,  it  is  necessary  to 
move  the  sieve  from  one  place  to  another  till  the  whole  charge  is  intro- 
duced; the  surface  is  then  made  even,  and  the  charge  is  ready  for 
chlorinatiori. 

The  chlorine  gas  is  produced  in  a  leaden  vessel,  as  shown  in  Figs. 
6  and  7  ;  the  first  is  a  vertical  cross-section,  the  second  a  top  view 


Remedies.  109 

with  the  cover  on.  The  circular  tub  a  has  an  outer  ring  c  six 
inches  deep,  for  the  reception  of  the  ring-shaped  side  of  the  cover  b. 
A  similar  small  ring  dl  is  on  the  top  of  the  cover  which  receives  the 
collar  e,  fastened  to  the  leaden  stirrer  /.  There  is  also  a  short  leaden 
pipe  g,  bent  in  the  shape  of  the  letter  S,  through  which  the  sulphuric 
acid  is  introduced,  the  outer  end  forming  a  funnel  for  this  purpose. 
Another  lead  pipe  d  conveys  the  chlorine  to  the  vat.  The  cover  is 
taken  off,  and  for  a  charge  of  three  tons  of  roasted  sulphurets  is 
introduced  the  following  : 

30  Ib.  of  manganese  (peroxide)  pulverised, 

30  Ib.  to  40  Ib.  of  common  salt,  according  to  quality, 

75  Ib.  of  sulphuric  acid  of  66  deg.,  and 

45  Ib.  of  water. 

The  water,  salt,  and  manganese,  are  introduced  first,  and  the  generator 
covered.* 

The  two  rings  c  and  dl  are  filled  with  water,  and  thereby  the  con- 
tents of  the  generator  shut  up  air-tight,  with  the  exception  of  the 
two  lead  pipes  g  and  d  of  the  cover.  The  gas  generator  stands  over 
a  small  furnace,  as  represented  by  b,  Fig.  5.  The  sulphuric  acid  is 
now  introduced  through  the  pipe  g,  Fig.  6,  but  not  all  at  once.  Three 
bottles  are  generally  sufficient  to  create  so  much  heat  that  the  develop- 
ment of  the  gas  takes  place  in  sufficient  quantity*  No  fire  is  yet  made 
under  the  generator.  The  chlorine  is  not  conveyed  directly  to  the 
chlorination  vats,  but  through  a  purifying  apparatus,  as  represented  in 
Fig.  8.  An  ordinary  wash-basin,  or  some  other  similar  vessel  A, 
receives  two  lead  pipes  (fin.);  one  of  them,  d,  conveys  the  chlorine 
from  the  generator,  and  is  bent  a  little  upwards  ;  the  other  is  bent  in 
the  same  way  but  stands  higher.  Both  ends  are  covered  with  a  bottle, 
the  bottom  of  which  is  cut  off.  There  is  sufficient  clean  water  in  the 
dish  to  stand  J  in.  or  f  in.  above  the  mouth  of  the  pipe  c?,  so  that  all 
the  gas  which  enters  the  space  in  the  bottom  is  forced  through  the 
water,  which  takes  up  the  muriatic  acid.  The  chlorine  passes  then 
through  the  pipe  du,  which  is  as  long  as  may  be  required  by  the 
distance  of  the  vat,  enters  the  space  below  the  false  bottom,  and 
gradually  permeates  the  ore.  The  water  through  which  the  gas  passes 
absorbs,  if  cold,  about  two  and  a  half  volumes  of  the  chlorine,  and  is 
then  saturated,  but  is  still  good  for  the  purpose  of  taking^  up  muriatic 
acid.  The  warmer  the  water  is,  the  less  chlorine  is  absorbed.  It  is, 
therefore,  wrong  to  introduce  a  continual  stream  of  cold  water  into  the 

*  The  leaden  gas  generator  costs  about  120  dols.  The  bottom  is 
made  of  1 6  Ib.  and  the  sides  and  cover  of  8  Ib.  sheet  lead. 


110  Remedies. 

wash-basin  A,  as  is  done  in  some  places,  as  a  good  deal  of  the  chlorine 
is  lost  thereby.  The  water  in  the  basin  may  be  renewed  once  or  twice 
during  the  operation  with  warm  water. 

This  apparatus  is  not  only  for  the  absorption  of  muriatic  acid — since, 
if  a  portion  of  this  should  happen  to  enter  the  vat,  and,  forming  sul- 
phuretted hydrogen,  precipitate  metallic  gold,  this  would  be  converted 
again  into  chloride  in  presence  of  abundant  chlorine — but  the  apparatus 
is  an  indispensable  indicator  of  the  gas  generator.  The  bottle  6, 
Fig.  8,  must  show  greenish  gas,  and  the  bubbling  from  the  pipe  d 
must  be  very  lively.  If  this  should  not  be  the  case,  another  bottle  of 
sulphuric  acid  must  be  introduced,  and  the  addition  continued  as  often 
.as  the  development  of  the  gas  becomes  weaker.  After  the  last  bottle 
has  been  used  up  a  moderate  fire  must  be  made  below  the  gas  generator. 
The  arch  0,  Fig.  5,  is  very  flat,  and  only  2  in.  thick  in  the  middle. 
Care  must  be  taken  to  have  a  J  in.  layer  of  sand  over  the  arch ;  an  open 
crack  would  cause  the  melting-  of  the  bottom  of  the  lead  vessel.  It  is 
also  necessary  to  turn  the  stirrer  f,  Fig.  6,  now  and  then  carefully  to 
prevent  the  caking  of  the  ingredients. 

The  vat,  after  the  ore  has  been  sifted  in,  as  before  described,  is  left 
uncovered.  It  takes  from  three  to  six  hours  before  the  gas  reaches  the 
top  of  the  charge.  The  progress  can  be  easily  watched  by  taking 
samples  from  underneath  the  surface.  The  smell  of  the  chlorine  shows 
how  high  it  has  penetrated.  When  the  chlorine  odour  is  perceived 
within  a  few  inches  of  the  surface  of  the  charge,  the  cover  is  laid  over 
the  vat,  and  the  edge  i,  Fig.  4,  all  round  the  cover,  luted  with  dough 
of  wheat-flour.  If  there  be  any  cracks  in  the  cover,  they  must  be 
carefully  pasted  so  that  no  chlorine  can  escape  anywhere.  The  only 
opening  not  shut  is  a  hole  of  1  in.  diameter,  k  •  but  as  soon  as  the  gas 
commences  to  escape,  that  is  plugged  up  with  dough.  The  circular 
opening  I  in  the  cover  is  only  proposed  by  the  author,  and  explained 
further  on.  The  chlorine  is  now  permitted  to  operate  on  the  gold  for 
twelve  to  eighteen  hours  (it  may  be  added  that,  as  the  sifting  requires 
some  time,  if  the  charge  amounts  to  3  or  6  tons,  the  gas  generator 
can  be  put  in  operation  before  the  vat  is  entirely  filled  with  ore,  because 
the  ascension  of  the  chlorine  is  also  slow).  The  pipe  dn  is  removed 
and  the  hole  plugged  up.  All  the  apparatus  must  be  examined  at 
intervals  to  see  that  there  is  no  loss  of  gas,  or  at  least  whenever  such 
loss  should  be  perceived  by  the  odour.  For  this  purpose  ammonia 
serves.  A  glass  rod  dipped  into  it  and  carried  close  around  the  place 
where  the  loss  indicated  by  the  smell  will  immediately  give  off  white 
fumes  when  in  contact  with  the  chlorine,  and  show  the  place  where  it 
escapes.  To  prevent  the  drying  of  the  dough  around  the  cover,  it  may 


Remedies.  Ill 

be  covered  with  strips  of  wet  cloth.  For  the  production  of  chlorine  the 
following  is  also  used : — one  part  manganese,  two  parts  muriatic  acid, 
one  part  sulphuric  acid,  diluted  with  one  part  water. 

Lixiviation. — After  twelve — or  if  the  sulphurets  contain  coarser 
gold,  after  fifteen  to  eighteen — hours  the  cover  is  taken  off  and  water 
introduced.  If  it  should  happen  that  in  taking  off  the  cover  no  gas  is 
found  over  the  ore,  it  is  advisable  to  shut  the  vat  and  to  impregnate  the 
•ore  again  with  chlorine  immediately,  as  in  nine  times  out  of  ten  the  ex- 
traction of  gold  will  fall  short.  This,  however,  does  not  occur  often 
with  proper  management.  The  water  should  flow  in  quickly  and  in 
such  a  way  as  not  to  strike  on  one  point — producing  a  deep  hole  in  the 
mass.  The  cock  e  is  shut,  and  the  waterflow  continues  until  the  surface 
of  the  charge  is  covered  and  no  air  bubbles  appear.  The  water  is  then 
stopped  and  the  cock  e  opened. 

A  small  stream  of  water  into  the  vat  must  replace  as  much  as  flows 
through  e,  so  that  the  surface  of  the  ore  is  always  covered. 

The  respiration  of  the  chlorine  is  injurious,  and  it  is  therefore  advis- 
able to  avoid  the  inhaling  of  the  gas  as  much  as  possible  by  leaving  the 
room  until  the  gas  disappears.  The  best  way  would  be  to  have  an  ar- 
rangement by  which  the  gas  is  carried  out  of  the  building ;  for  instance, 
to  put  a  movable  wooden  pipe  6  in.  square  about  the  proposed  opening 
I.*  In  order  to  prevent  the  stream  of  water  from  making  a  hole  into 
the  ore  a  perforated  wooden  distributor  fixed  to  the  cover,  as  shown  in 
the  drawing,  would  answer  the  purpose. 

A  trough  below  the  cock  e  receives  the  solution  and  conveys  it  into 
the  precipitating  tub  e  (Fig.  5).  The  trough  must  be  lined  with  sheet 
lead,  avoiding  sharp  corners  ;  or  it  must  be  at  least  well  coated  with  tar 
,and  pitch  in  default  of  sheet  lead.  Great  care  must  be  taken  to  pre- 
vent the  waste  of  the  solution.  Not  a  drop  of  it  ought  to  be  seen 
outside  of  the  trough. 

The  precipitating  vat  e,  Fig.  5,  is  a  wooden  tub  like  the  chlorination 
vat,  Fig.  4,  but  without  a  false  bottom.  The  staves  must  fit  together 
perfectly.  One  4  ft.  in  diameter  and  3  ft.  high  is  sufficient  to  receive 
the  solution  of  3  tons  of  ore.  Deetken's  10-ft.  vat  containing  6  tons  of 
sulphurets  requires  two  precipitating  vats,  one  is  5  ft.,  the  other  6  ft. 
in  diameter,  each  2  ft.  high.  The  vats  ought  to  be  lined  with  sheet 
lead,  and  a  more  proper  shape  would  be  a  rectangular  box  with  a  half- 

*  More  convenient  would  be  a  leaden  pipe  through  the  side  of  the  rat 
near  the  top,  through  which  the  gas  is  forced,  by  the  entering  water,  out 
of  the  building.  In  this  case  the  water  would  have  to  be  conveyed  by 
-an  india-rubber  hose  through  the  opening  I  of  the  same  size  with  the 
Jiose. 


112  Remedies. 

round,  somewhat  inclined,  sheet  lead  bottom,  which  permits  an  easier 
and  better  cleaning.  In  default  of  a  lead  lining  the  vats  must  be  coated! 
with  a  mixture  of  pitch  and  tar,  otherwise  the  wood  absorbs  some  of 
the  gold  solution.  A  better  and  smoother  coating  is  obtained  by  the 
use  of  the  so-called  "  asphaltum  cement,"  which  should  be  applied  twice 
before  it  is  ready  for  use,  as  the  cement  is  too  liquid  for  a  single  coating. 
A  very  smooth  surface  of  the  vat  is  important,  else  it  is  difficult  to 
gather  all  the  finely  precipitated  gold. 

From  time  to  time  samples  are  taken  in  a  clean  tumbler  of  white 
glass  from  the  solution  at  the  end  of  the  trough,  and  observed  in  refer- 
ence to  the  point  whether  an  addition  of  a  clear  solution  of  sulphate  of 
iron  (green  vitriol)  causes  a  dark  precipitate.  If  the  solution  after  the- 
addition  of  the  precipitant  should  remain  perfectly  clear,  the  water 
supply  in  the  chlorination  vat  must  be  stopped  and  all  the  liquid  con- 
tents of  the  vat  permitted  to  flow  into  the  precipitating  vat. 

Precipitation. — The  precipitant  for  the  gold  is  a  solution  of  sul- 
phate of  iron.  It  is  known  also  under  the  name  of  "  copperas  "  or  green 
vitriol,  and  forms  light  green  crystals.  Dissolved  in  water  (in  a  barrel 
20  in.  or  22  in.  in  diameter  and  about  3  ft.  high)  it  generally  makes  a- 
muddy  solution  and  gives  a  light  sediment  which  must  not  be  disturbed 
in  drawing  off  the  clear  solution  from  above  it.  For  this  purpose  a 
leaded  syphon  will  answer.  It  is,  however,  better  economy  to  prepare 
the  precipitant  fresh  in  the  chlorination  works.  In  a  barrel  or  tub  of 
about  10  cubic  feet  content,  50  Ib.  to  60  Ib.  of  pieces  of  old  wrought 
iron  are  introduced,  then  five  or  six  buckets  of  water  and  20  Ib.  to 
30  Ib.  of  sulphuric  acid.  This  is  prepared  two  or  three  days  before  the 
solution  is  wanted.  One  or  two  buckets  of  this  iron  solution  must  be 
introduced  into  the  precipitating  vat  before  the  gold  solution  is  allowed 
to  flow  in,  so  that  the  precipitation  may  begin  immediately.  After  this 
as  much  of  the  precipitant  is  added  as  is  required,  which  can  be  ascer- 
tained by  taking  a  sample  out  of  the  precipitating  vat,  filtering  it  through 
filtering  paper,  and  mixing  it  with  the  precipitant.  If  the  mixture  should 
darken  a  little  after  a  time  some  more  of  the  iron  solution  must  be 
introduced  into  the  precipitating  vat.  The  precipitated  gold  requires- 
some  time  before  it  is  all  deposited  on  the  bottom.  The  fluid  must 
appear  perfectly  clear  before  the  water  can  be  drawn  off.  Generally 
the  mixture  stands  undisturbed  over  night.  The  upper  plug  g  (Fig.  5} 
is  removed  and  the  clear  liquid  conveyed  into  another  vessel  f,  of  suffi- 
cient capacity,  till  it  is  nearly  all  run  out  of  the  precipitating  tub- 
through  all  the  plug-holes.  The  discharge  must  be  performed  carefully 
so  that  the  flow  appears  always  clear.  It  is  better  if  several  chlorina- 
tions  have  been  performed  before  the  gold  is  taken  out,  as  there  is  a, 


Remedies.  113 

less  percentage  of  loss  by  wastage  with  a  large  quantity  of  gold.  This 
is  dipped  out  carefully  by  means  of  a  dipper  or  scoop  into  a  clean 
porcelain  dish  or  enamelled  vessel,  and  the  rest  washed  out  through  the 
lowest  cock.  It  is  well  to  apply  a  jet  of  water  over  the  sides  and 
bottom  in  order  to  wash  off  all  precipitated  gold. 

The  gold  obtained  is  then  introduced  into  a  filter  of  filtering  paper, 
and  subsequently  dried  in  an  iron  or  porcelain  vessel  in  a  warm  place 
or  over  a  fire.  For  the  purpose  of  melting  the  black  lead  crucibles  are 
less  suitable  than  "Hessian"  or  clay  crucibles;  from  the  latter  a  purer 
gold  is  obtained.  A  little  salt,  some  borax,  and  saltpetre  (nitrate  of 
potash)  are  added  as  fluxes. 

COST   OP   THE    CHLORINATION    PROCESS    PER   TON   OP    ORE. 

If  the  ore  is  roasted  in  a  long  or  double  furnace  a  ton  of  well  roasted 
sulphurets  can  be  drawn  out  every  eight  hours,  that  is,  3  tons  in  twenty- 
four  hours.  The  working  expenses  of  twenty-four  hours  may  be  given 
.as  follow: 

$ 
Superintendence       ...          ...          ...          ...          ...  6.00 

Four  roasters  at  $3.50         H.OO 

Three  cords  of  wood  at  |4 12.00 

Thirty  pounds  manganese  at  6^  c.              ...          ...  1-87^ 

Forty  pounds  salt  at  |  c ..  .30 

Seventy-five  pounds  sulphuric  acid  at  2J  c.            ...  1.87J 

One  man  at  the  vats,  two  days  at  $3.50   ...          ...  7.00 

Sulphate  of  iron       ...          ...          ...          ...          ...  60 

Total  cost  of  3  tons         $43. 65 

Or  $14.55  per  ton  of  sulphurets. 

That  the  foregoing  process  is  in  general  use  in  the 
United  States,  and  other  parts  of  North  and  South 
America,  may  be  judged  by  the  following  plan  and 
excerpt  from  the  catalogue  of  1885  of  Messrs.  Fraser  and 
Chalmers,  Chicago,  &c.,  who  are  probably  the  most 
enterprising  manufacturers  of  metallurgical  machinery  in 
the  world,  and  who,  had  there  been  anything  better  de- 
vised, would  assuredly  have  endeavoured  to  introduce  it. 

CHLORINATION  MILL. 
This  mill  and  process  as  used  in  connection  with  a  gold  mill  for 


114 


Remedies. 


treating  the  concentrates  from  the  Frue  vanners  is  clearly  illustrated 
in  an  article  recently  published  describing  the  Providence  Mill,  Grass 
Valley  District,  California,*  which  we  reproduce  : 

"  The  ore  treated  is  quartz,  carrying  free  gold,  pyrites,  galena,  chal- 
copyrite,  arsenopyrite,  and  zinc  blende.  It  is  first  crushed  in  rock 
breakers  and  then  stamped  fine  enough  to  pass  through  a  forty-mesh 
sieve.  Then  it  passes  as  a  slime  over  silver-plated  copper  amalgamat- 
ing plates  to  Frue  concentrators.  The  free  gold  is  caught  in  the  stamp 


Fig.  3. 


batteries  and  on  the  plates,  the  sulphurets  are  collected  by  the  concen- 
trators. The  latter  are  dried  and  then  roasted,  chlorinated  and  leached. 
The  roasting  is  done  in  a  three  story  reverberatory  furnace.  About 
1  per  cent,  of  salt  is  added  near  the  close  of  the  operation.  All  the 
sulphur,  arsenic,  and  antimony  are  expelled  and  the  iron  and  other  base 
metals  oxidised.  The  gold  is  left  in  a  free  metallic  state,  the  silver 
being  partly  concentrated  into  a  chloride  by  the  salt. 

"  The  roasted  ore  is  then  transferred  to  chlorinating  tubs,   holding 

from  2  to  3  tons  each.     The  covers  are  put  on  and  the  joint  caulked 

with  rags  and  luted  with  dough  to  make  it  gas-tight.     The  tubs  have 

false  bottoms,  full  of  holes  and  covered  with  sacking.     Chlorine  gas, 

*  Near  where  Deetken  worked  twenty-seven  years  previously. 


Remedies.  115 

made  from  salt,  black  oxide  of  manganese,  and  sulphuric  acid,  is  then 
introduced  below  the  false  bottom  and  allowed  to  permeate  the  ore. 
Two  or  three  days  are  required  for  their  permeation.  The  gold  and 
silver  are  thus  concentrated  into  chlorides.  The  chloride  of  gold  is 
leached  out  by  water  added  at  the  top  and  drawn  off  at  the  bottom  and 
run  into  precipitating  tanks.  The  gold  is  precipitated  in  a  fine  metallic 
state  by  the  addition  of  sulphate  of  iron.  The  water  is  then  run  off,  the 
gold  collected  and  dried,  melted  in  graphite  crucibles  and  cast  in  bars. 

"  The  silver  chloride  remaining  in  the  ore  is  dissolved  out  by  a 
solution  of  hyposulphite  of  calcium.  The  solution  is  run  into  other 
tanks  and  the  silver  precipitated  as  a  sulphide  by  adding  calcium 
polysulphide.  The  sulphide  of  silver  is  dried,  roasted,  and  then  melted 
and  cast  into  bars.  The  cost  of  milling  and  treating  the  sulphurets  is 
1.37  dols.  per  ton  of  ore." 

One  of  the  main  faults  of  this  process  is  the  great 
length  of  time  necessary  for  the  chlorine  gas  to  permeate 
the  ore  and  dissolve  the  gold,  also  the  time  occupied  in 
the  filtration  and  subsequent  separation  of  the  metal  from 
liquid  and  its  surroundings.  Taking  as  a  basis  the  state- 
ments put  forward  by  Messrs.  Fraser  and  Chalmers,  a 
mine  turning  out  100  tons  of  ore  daily  would  require  to 
run  without  stoppages,  at  least  100  vats,  this  is  a  triple 
vat  capacity  to  that  required  for  one  day's  output,  and 
creates  a  very  considerable  item  both  in  cost,  and  shed 
capacity,  to  which  should  be  added  at  least  another 
hundred  vats  to  take  the  leachings  from  the  chlorinated 
ore,  prior  to  the  precipitation  of  the  gold  ;  so,  for  a  mine 
of  the  specified  output,  some  200  vats  would  be  required ; 
yet,  with  a  mine  turning  out  ore,  from  which  the  aggre- 
gate quantity  requiring  chlorination  amounts  to  only  a 
few  tons  per  week,  this  is  still  perhaps  the  most  econo- 
mical process. 

HENDERSON,  1859. 

Mr.  Wm.  Henderson's  patent,  No.  883,  is  dated  April 
8th,  1859,  and  refers  to  the  following  : 


116  Remedies. 

Improvements  in  treating  certain  ores,  and  in  obtaining  products 
therefrom,  to  be  as  follows  : 

These  improvements  relate,  first,  to  the  treatment  of  zinc  ores,  or 
other  ores  containing  zinc  ;  secondly,  to  the  treatment  of  ores  of  anti- 
mony that  contain  lead  and  other  metals ;  thirdly,  to  the  treatment  of 
copper  ores ;  fourthly,  to  the  treatment  of  ores  or  products  containing 
cobalt ;  fifthly,  to  the  treatment  of  gold  and  silver  ores  and  auriferous 
quartz ;  and,  lastly,  to  the  dressing  of  lead  and  other  ores. 

From  this  specification  extracts  are  made  which  refer 
to  the  principal  points  of  his  method  of  treating  gold,  and 
silver  ores.  In  his  procedure  he  follows  previous  chlori- 
nators  to  this  point : 

When  the  ores  are  very  soft  and  friable  it  is  necessary  to  work  them 
in  round  agitators  (1).  I  prefer,  however,  to  work  these  ores  in  vats 
with  false  bottoms,  when  at  all  practicable.  A  vat  having  been  filled 
with  the  powdered  ore,  I  cover  the  whole  surface  of  the  ore  with 
muriatic  acid,  of  about  15  deg.  Twaddle's  hydrometer,  and  allow  it  to 
penetrate  through  the  body  of  ore.  The  acid  must  not  contain  any  free 
chlorine.  When  the  whole  of  the  ore  has  been  wetted  with  muriatic 
acid  it  is  allowed  to  rest  for  a  few  hours.  The  liquor  is  then  washed 
out  with  water  until  perfectly  tasteless.  By  this  means  I  separate  all 
oxides  and  earths  soluble  in  muriatic  acid ;  if  these  are  of  any  value 
they  may  be  separated  from  the  solution  as  previously  described  (2). 
The  quartz  thus  prepared  is  now  covered  with  aqueous  solution  of 
chlorine,  and  the  solution  of  the  gold  at  once  takes  place.  A  gentle 
heat  much  facilitates  the  solution.  The  liquor  during  the  process  of 
solution  should  be  repeatedly  pumped  to  the  top  of  the  ore  and  allowed 
to  penetrate  under  the  false  bottom,  leaving  the  top  of  the  ore  dry,  and 
as  soon  as  this  occurs  it  must  be  all  pumped  to  the  top  again,  so  as  to 
keep  up  a  constant  circulation.  If  these  directions  are  carefully 
attended  to,  the  whole  of  the  gold  will  be  dissolved  out  from  even  rich 
quartz  in  twenty-four  hours  (3).  The  chloride  of  gold  is  then  removed 
to  another  vessel,  and  a  sample  of  the  ore  tested  for  gold  ;  if  any  remains 
undissolved,  a  further  quantity  of  solution  of  chlorine  is  added  until  the 
ore  is  exhausted.  It  is  then  washed  thoroughly  clean  and  the  washings 
added  to  the  original  solution.  The  solution  of  gold  thus  obtained  is 
then  boiled  by  a  jet  of  steam  to  liberate  the  free  chlorine  (see  Hears 
subsequently).  If  this  is  done  in  a  close  vessel  the  chlorine  gas  may 
be  again  condensed  by  passing  it  through  cold  water.  When  the 
boiling  solution  smells  no  longer  of  chlorine  the  gold  is  then  precipi- 
tated by  protosulphate  of  iron,  oxalic  acid,  or  any  other  precipitant  (4). 


Remedies.  117 

....  In  some  varieties  of  gold  quartz  the  gold  is  only  partially  dis- 
solved, sometimes  not  at  all,  by  aqueous  solution  of  chlorine,  nor  by 
chlorine  in  the  gaseous  state  (5).  These  ores  I  treat  in  the  following 
manner: — I  treat  the  ore  either  before  or  after  the  washing  with  weak 
muriatic  acid ;  if  the  latter  I  dry  it,  and  then  intimately  mix  it  with 
from  1  to  5  per  cent,  of  good  peroxide  of  manganese  (or  other  oxide 
capable  of  liberating  chlorine  from  muriatic  acid)  in  fine  powder.  I 
then  moisten  this  mixture  with  strong  muriatic  acid  of  at  least  1.125 
specific  gravity,  turning  over  the  heap  so  as  to  ensure  that  every  part 
has  been  moistened.  The  heap  is  then  gathered  closely  together,  and 
allowed  to  heat  of  its  own  accord  in  a  dry  place  for  twenty-four  hours. 
At  the  end  of  that  time  it  should  be  transferred  to  the  vats  with  false 
bottoms,  and  the  vats  filled  (6).  Steam  of  a  high  pressure  (say  60  Ib.) 
is  then  slowly  introduced  under  the  false  bottom,  from  which  it  will 
gradually  penetrate  upward  through  the  whole  mass  of  ore  (see 
Primard  previously},  dissolving  the  chlorides  of  gold  and  manganese, 
which  are  drawn  off  from  under  the  false  bottom  into  another  vessel, 
and  the  ore  may  then  be  entirely  exhaused  by  washing  with  hot 
water  (7).  The  gold  will  be  readily  obtained  from  this  solution  by 
boiling  with  protosulphate  or  protochloride  of  iron.  I  prefer  the 
former.  A  mixture  of  common  salt  and  oxide  of  manganese  may  be 
mixed  with  the  ore,  and  then  the  mixture,  moistened  with  concentrated 
sulphuric  acid,  may  be  substituted  for  the  oxide  of  manganese  and 
muriatic  acid  ;  but  I  prefer  the  latter  as  simpler  and  cheaper  (8). 

(l.)  This  appears  to  be  an  ambiguous  reference  to 
barrel  chlorination. 

(2.)  From  an  economical  point  of  view  such  procedure 
is  quite  impracticable,  and  might  result  in  producing 
arsenuretted  hydrogen,  a  very  deadly  gas. 

(3.)  Such  procedure  would  be  impracticable  except 
with  clean  quartz,  for  with  ores  that  produced  slimes  a 
rapid  clogging  would  result,  and  the  liquor  could  not  be 
continually  passed  through  them. 

(4.)  This  boiling  method  can  only  be  regarded  in  the 
light  of  a  laboratory  experiment  ;  from  the  leaching  the 
resultant  liquid  must  be  at  least  equal  in  quantity  to  the 
bulk  of  ore  treated,  and  the  whole  solution  would  have 
to  be  boiled  in  a  vessel  not  acted  upon  by  chlorine.  The 


118  Remedies. 

value  of  the  chlorine  saved  would  not  pay  for  boiling 
and  condensation. 

(5.)  It  is  difficult  to  arrive  at  what  the  patentee  here 
means. 

(6.)  This  appears  to  be  the  first  suggestion  for  the 
generation  of  chlorine  within  the  ore  mass  in  the  manner 
described.  Duflos  and  Lange,  in  1848-9,  both  generated 
chlorine  in  the  ore  when  in  the  chlorinating  vessels ;  the 
advantage  of  generating  chlorine  in  the  ore  before  put- 
ting it  into  the  vats  is  not  very  apparent.  The  quantity 
of  muriatic  acid  required  precludes  the  carrying  out 
this  method  within  the  limits  of  economy  on  a  goldfield. 

(7.)  This  is  an  inverted  method  of  Primard's  leaching 
process,  as  he  introduced  the  steam  on  the  top  of  the  ore. 

(8.)  With  perfect  mechanical  arrrangements  these 
suggestions  are  good. 

The  remainder  of  the  patent  specification  deals  with 
the  subject  of  crushing  by  rolls,  which  are  favoured  by 
Mr.  Henderson.  Similar  views  to  those  expressed  by 
him  have  been  lately  put  forward  as  original  by  several 
writers  on  the  subject. 

TOUSSAINT   AND   LANGLOIS,  1859. 

For  the  patent,  No.  956,  issued  to  Messrs. Toussaint  and 
Langlois,  of  Paris,  the  provisional  specification  is  dated 
16th  April,  and  the  specification  14th  October,  1859, 
from  which  the  portions  referring  to  chlorination  are 
abstracted  : 

This  invention  relates  to  apparatus  for  the  separation  of  ores  of  gold, 
silver,  and  other  minerals.  This  separation  is  performed  in  three 
different  ways  by  chloruration,  the  application  of  a  column  of  water, 
and  by  amalgamation. 

The  first  apparatus  for  effecting  the  chloruration  permits  of  creating 
a  vacuum  before  the  introduction  of  the  reducing  agent,  which  then 
permeates  the  ore  without  resistance,  and  completely  saturates  it.  The 


Remedies. 


119 


metallic  chlorides  are  after  the  operation  treated  in  the  ordinary  way. 
I  have  represented  in  the  drawing  (Fig.  10)  a  complete  apparatus  for  the 
treatment  of  ores  of  precious  metals  by  means  of  chlorine,  a,  wood  recep- 
tacle lined  with  lead  to  contain  the  ores  ;  b,  cover  of  the  receptacle  on 
which  it  is  firmly  bolted ;  c,  masonry  supporting  the  receptacle  a ;  d, 
funnel  cock  of  lead  placed  on  the  cover  6,  which  serves  for  the  introduc- 
tion of  the  ore  into  the  receptacle  a ;  e,  vacuum  gauge ;  f,  ordinary 
gauge  ;  <?,  cock  for  the  escape  of  the  steam  introduced  in  the  receptacle  ; 
A,  india-rubber  packing  placed  between  the  top  of  the  recipient  and  the 
•cover  to  render  the  closure  hermetic ;  i,  tube  furnished  with  a  cock  for 
the  introduction  of  steam  and  chlorine  to  the  receptacle  a ;  j,  small 


leaden  tubes  placed  on  the  sides  of  the  receptacle  ;  they  are  in  commu- 
nication with  the  receptacle  containing  the  chlorine  and  with  the  recep- 
tacle a  \  they  are  covered  with  sheets  of  lead  which  are  grooved  to  pre- 
vent the  ores  stopping  up  the  holes  which  are  pierced  in  them ;  k,  cock 
for  the  exit  of  the  liquids  contained  in  the  receptacle  a;  a  filter  is 
placed  at  the  mouth  of  the  receptacle  so  as  to  stop  the  fall  of  the  ores  ; 
I,  closed  vessel  furnished  with  a  man-hole,  and  serving  to  receive  the 
liquids  charged  with  metals;  m,  suction  pump  for  producing  the 
vacuum  and  pumping  out  the  water  remaining  in  the  receptacle  a  when 
the  vacuum  is  effected. 

The  treatment  of  the  ores  in  this  improved  apparatus  is  as  follows  : 
— The  ores  are  introduced  into  the  receptacle  a,  while  at  the  same  time 


120  Remedies. 

a  vacuum  is  effected  by  the  pump  (Mears  subsequently,  4=th  specification). 
The  action  of  the  pump  is  then  stopped,  and  the  chlorine  introduced  by 
means  of  a  cock  i,  until  a  complete  chloruration  of  the  ores  is  effected ; 
the  cock  k  is  then  opened,  and  the  metallic  chlorides  obtained  descend 
into  the  closed  vessel  I,  and  are  then  treated  in  the  ordinary  way. 

This  method  appears  to  be  the  first  attempt  to  intro- 
duce rapid  chlorination.  The  object  of  creating  the 
vacuum,  before  charging  with  chlorine,  was  that  the  gas 
should  permeate  the  ore  mass  quickly,  instead  of  gradually 
as  in  others,  and  also  that  its  strength  should  be  undiluted 
by  atmospheric  air;  in  Mears'  fourth  and  last  specification, 
1880,  and  subsequently  in  Evans',  1882,  claims  are  laid  to 
having  discovered  this  method.  Messrs.  Toussaint  and 
Langlois  approached  very  closely  a  point  of  considerable 
importance ;  if,  instead  of  leaching  in  the  ordinary  way  by 
gravitation,  they  had  utilized  their  vacuum  pump  for 
leaching  rapidly  in  the  same  manner  as  for  the  rapid 
introduction  of  chlorine,  subsequent  patentees  could  not 
have  sustained  a  claim  for  rapid  filtration  by  means  of  a 
vacuum  pump,  though  it  must  by  no  means  be  assumed, 
judging  by  the  light  of  patents  granted  on  this  subject, 
that  the  Patent  Office  would  not  have  granted  an  exclu- 
sive license  for  such. 

COBLE Y  AND  WRIGHT,  1862. 

For  the  patent,  No.  1005,  issued  to  Messrs.  Cobley 
and  Wright,  the  provisional  specification  is  dated  April 
8th,  and  the  specification  October  8th,  1862;  there  is 
no  drawing  ;  the  preamble  is  as  follows  : 

An  invention  for  improvements  in  the  method  of  and  the  apparatus 
for  treating  auriferous  and  argentiferous  minerals  and  ores  for  the 
purpose  of  extracting  and  separating  the  gold  and  silver  from  the 
other  metals,  minerals,  and  substances  combined  therewith ;  also  in 
the  method  of  treating  the  various  residues  resulting  therefrom,  and 


Remedies.  121 

in  the  utilization,  application,  and  uses  of  the  said  residues  when  so 

treated 

The  auriferous  and  argentiferous  minerals  and  ores  which  we  propose 
to  treat  we  classify  in  the  following  manner,  as  each  class  require 
modifications  in  the  mode  of  treatment. 

The  foregoing  sentence  is  very  true,  and  had  this 
necessity  been  recognized  during  years  past  by  mill-men, 
much  of  the  money  hopelessly  lost  in  endeavouring  to 
work  mining  properties  by  unsuitable  methods  would 
have  been  most  productive. 

The  first  part  of  the  specification  is  taken  up  in  des- 
cribing a  complicated  and  entirely  impacticable  grinding 
process.  Particulars  are  then  given  of  a  method  of 
treating  arsenical  and  antimonial  ores,  which  are,  in 
reality, -test-tube  reactions,  only  feasible  with  laboratory 
samples,  and  in  practice  out  of  the  question  from  all 
points  of  view.  Excerpts  are  made  of  the  portions  re- 
ferring to  chlorination  : 

Obtain  the  materials  in  the  state  of  a  fine,  soft,  pulpy  mass.  This 
mass  is  then  introduced  into  a  vat  or  vessel  for  the  purpose  of  treating 
with  solvents  in  order  to  form  soluble  compounds  with  the  gold.  The 
solvents  used  are  either  gaseous  chlorine,  obtained  from  chloride  of 
magnesium,  and  peroxide  of  manganese  formed  in  a  separate  vessel  and 
passed  into  the  silicious  pulp  by  means  of  pipes ;  when  sufficient  gas 
has  been  passed  into  it  we  agitate  the  mass  by  means  of  agitators 
inserted  in  the  vessel  (1)  (  De  Lacy  later),  and  then  filter  or  decant 
the  solution  formed,  which  contains  chloride  of  gold,  and  precipitate 
the  gold  by  means  of  tin  or  its  protochloride  or  protosulphate  of  iron, 
or  other  well-known  precipitants,  or,  instead  of  precipitating,  we  distil 
the  solution,  obtaining  a  powder  of  gold.  In  some  cases,  instead  of 
using  gaseous  chlorine,  we  introduce  into  the  silicious  mass  a  mixture 
of  hydrochloric  acid  (2)  and  chloride  of  lime  (Duflos  and  Lange  pre- 
viously, and  De  Lacy  and  Hears  subsequently)  or  nitro-hydrochloric 
acid  in  a  concentrated  form,  and  in  order  to  accelerate  the  chemical 
action  we  raise  the  temperature  and  agitate  the  mass  as  before  men- 
tioned ;  we  then  filter  or  decant  the  solution,  which  contains  chloride 
of  gold,  and  precipitate  this  by  precipitants  or  by  distillation  as  before 
mentioned.  We  continue  to  use  the  solvents  before  referred  to  over 


122  Remedies. 

and  over  again  on  fresh  charges  as  long  as  we  find  that  any  solvent 
power  remains  in  them  (3). 

(1.)  These  gentlemen  appear  to  be  the  first  to  suggest 
agitation  during  chlorination  by  means  of  a  stirrer,  but 
such  method  would  be  more  difficult  and  costly  than  a 
rotating  barrel. 

(2.)  At  the  time  the  patent  was  taken  out  hydro- 
chloric acid  was  a  waste  product  in  England  ;  but  at 
present,  in  the  majority  of  cases,  such  a  chemical  would 
be  outside  economical  consideration  on  a  goldfield,  owing 
to  cost  and  difficulties  of  transit. 

(3.)  The  using  of  a  gold  solution  over  and  over  again 
would  be  a  most  risky  operation,  and  its  practical  diffi- 
culties preclude  its  application  outside  a  laboratory. 

The  remainder  of  the  specification  deals  with  the  treat- 
ment of  the  residues  ;  the  examples  cited  there  are  pretty, 
and  are  further  instances  of  test-tube  chemistry. 

DEETKEN,  1863. 

Mr.  Deetken  took  out  a  patent  in  1863  in  the  United 
States  for  the  process  which,  according  to  Kustel,  he  had 


been   working    there   for   five   years    previously.       The 
following  abstract  and  accompanying   drawing  (Fig.  11) 


Remedies.  123 

are  all  the  information  obtainable  in  the  London  Patent 
Office  regarding  this  specification: 

No.  37,278.  Gustavus  F.  Deetken,  of  Nevada,  California,  Improved 
Apparatus  for  Extracting  Gold  from  Pyrites.  Patent  dated  January 
6th,  1863. 

The  pyrites  having  been  first  roasted,  is  placed  in  a  tight  vat,  and 
there  exposed  to  a  stream  of  chlorine  gas  ;  it  is  afterwards  washed,  and 
the  solution  of  various  chlorides  collected  and  precipitated  in  carboys. 

Claim.  —  The  combination  of  the  several  devices  and  apparatus  herein 
described,  and  operating  substantially  as  illustrated  and  explained. 


1864. 

Mr.  A.  C.  L.  De  Lacy's  patent,  No.  -£ff  Victoria,  is 
dated  August  25th,  1864,  and  refers  to  the  following: 

Improvements  in  machinery  and  processes  for  pulverizing  gangue 
and  the  extraction  of  gold  and  other  metals  from  mineral  substances, 
and  improvements  in  methods  for  the  generation  of  chlorine  used  in 
.such  processes. 

.There  were  two  specifications,  the  patent  office  allowing 
the  amended  to  stand  in  lieu  of  the  original  specification, 
the  subject  matter  of  the  latter  being  only  slightly 
altered. 

It  is  frequently  noticeable  that  one  of  the  stumbling 
blocks,  rendering  the  work  of  inventors  abortive,  is  that 
the  inventive  mind  is  sometimes  of  too  comprehensive  a 
character  ;  for  instance,  the  man  with  a  sound  chemical 
knowledge  often  fondly  believes  himself  to  be  a  born 
mechanician  and  vice  versa.  This  particular  inventor 
actually  proposed  to  shoot  ore  out  of  a  cannon  against  a 
target,  so  as  to  reduce  it  to  a  state  of  fine  pulverization. 
Such  a  singular  method  may  be  passed  without 
criticism. 

The  specifications  are  very  long  and  considerably 
involved  ;  excerpts  on  the  subject  matter  referring  to  the 


124  Remedies. 

present  inquiry  taken  from  the  amended  specification  are 
as  follows  : 

When  I  use  chloride  or  hydrochlorite  of  lime,  claimed  by  me  in  my 
patent,  18th  day  of  February,  1864,  for  the  extraction  of  gold,  I  mix 
such  chloric  compound  with  the  auriferous  substances  to  be  operated 
upon  by  means  of  a  puddling-machine  (Cobley  and  Wright  previously), 
with  a  pug-mill  or  other  contrivance,  composed  of  such  materials  as 
are  already  patented  by  me  in  the  said  patent,  or  as  are  herein  after 
described 

And  then  I  transfer  the  contents  of  the  puddling  machine  to  a  close 
vessel  of  the  same  material.  I  add  hydrochloric  or  sulphuric  acid 
diluted  with  hot  or  cold  water,  and  with  the  aid  of  heat  and  pres- 
sure (Hears  subsequently)  I  cause  the  gold  contained  in  the  substances 
operated  upon  to  be  dissolved.  I  then  draw  off  the  solution  and  wash 
the  insoluble  residue  and  ordinarily  use  the  washing  with  the  next 
charge  (Cobley  and  Wright  previously).  My  system  is  according  to 
the  nature  of  the  auriferous  substances  to  be  operated  upon,  either  to 
heat  them  with  aqueous  chlorine  or  to  mix  them  with  the  materials  for 
generating  chlorine  as  hereinbefore  described,  and  the  strength  of  the 
solvent  materials;  and  the  time  occupied  in  producing  their  perfect 
effect  depends  upon  the  nature  of  the  auriferous  substances  to  be 

operated  upon I  force  chlorine  gas  by  means  of  a  force  pump, 

bellows,  gasometer,  or  other  contrivance  (see  Mears  subsequently), 
into  the  vessels  containing  the  auriferous  matters  under  process 
for  the  purpose  of  keeping  up  the  strength  of  the  said  solution, 
when  the  chlorine  of  the  original  chloric  materials  have  been  expelled 
by  the  steam  applied  for  heating  purposes,  such  pump  or  other  contriv- 
ance being  composed  of  materials  not  acted  upon  by  chlorine 

When  the  substance  operated  upon  is  of  a  clayey  or  close  nature  I 
agitate  it  frequently  during  the  process  in  suitable  vessels,  such  as  are 
marked  in  the  accompanying  drawings,  Figs.  1 2  and  1 3,  and  hereinafter 
described  (Duflos  revolving  barrel,  Primard's  vertical  barrel),  and  main- 
tain the  heat  by  steam  or  otherwise  in  the  said  vessels  for  twenty- 
four  hours,  more  or  less,  adding  from  time  to  time  chlorine  gas  as 
long  as  may  be  necessary  to  extract  any  gold  remaining  undissolved.  .  . 
To  the  digesting  vessels  I  use  double  or  single  covers,  to  which  I  fix 
an  escape  gas  pipe  furnished  with  a  stop-cock  and  leading  to  a  chamber 
containing  milk  of  lime  to  recover  surplus  and  waste  chlorine  (see 
Pollok,  subsequently).  For  the  generation  of  chlorine  I  take  a  retort 
or  suitable  vessel  into  which  I  place  the  material  for  generation  of 
chlorine  with  or  without  the  addition  of  heat.  The  auriferous  sub- 


Remedies. 


125 


stances  to  be  operated  upon  may  be  placed  on  shelves  (see  Fig.  14)  in 
the  said  digesting  vessels,  which  should  contain  a  little  water  and  be 
connected  with  the  retort  or  vessel  for  generating  chlorine,  so  that  the 
chlorine  may  have  free  access  to  the  substances  under  operation.  I 
prefer  to  mount  the  digesting  chamber  on  trunnions  (Duflos,  Primard); 
I  cause  the  waste  gas  from  the  digesting  chamber  to  be  led  by  a  pipe 
into  the  before-mentioned  chamber  containing  the  lime  or  other  alkaline 
base,  which  I  stir  occasionally  with  an  agitator  (CoUey  and  Wright) 
or  by  any  other  means  ;  or  I  force  this  gas  into  the  vessels  holding  the 
auriferous  substances,  which  may  be  done  by  the  methods  hereinbefore 
described.  The  description  of  the  aforesaid  vessels  and  of  the  apparatus 


used  for  the  above-mentioned  purposes  is  as  follows — that  is  to  say, 
Fig.  12,  retort  gas  generator  or  digester  for  generating  chlorine  gas — 
«,  retort;  b,  vats  to  hold  materials;  c,  gas  escape  pipe  ;  d,  gas  pipes  from 
retort  or  digester  ;  e,  escape  pipe  to  milk  of  lime ;  f,  agitator ;  g, 
discharging  cocks ;  h,  false  bottoms ;  i,  gas  pipe ;  k,  steam  pipe  to 
retort  or  digester,  a  slab  on  bottom  holds  manganese ;  m,  framework ; 
n,  discharge  cock  from  retort ;  o,  steam  pipe ;  p  p,  man-holes  :  s  s, 
steam  pipes  to  vats ;  1 1,  receivers  of  liquid  pumped  up  into  pipes  ;  v  v^ 
perforated  distributor.  Fig.  13,  a,  vessel  which  is  kept  revolving  by 
a,ny  contrivance ;  6,  centre  hollow  core ;  c  c,  perforations ;  c?,  steam 


126 


Remedies. 


pipe ;  e,  gas  pipe  ;  f,  water  lute ;  g,  movable  gland  or  stuffing-box  •  kr 
escape  pipe ;  i,  man-hole  to  fill  or  discharge ;  k,  perforated  puddlers- 
fastened  to  the  interior  ;  I,  frame  ;  m,  winch  ;  n,  cogwheel. 

Fig.  14,  fixed  cask — a,  gas  pipe  with  water  lute  ;  6,  vessel ;  c,  man- 
hole with  water  lutes ;  d,  escape  pipe  with  water  lute ;  e,  pipe  commu- 
nicating with  arms  ffff\  fffj  hollow  arms  with  perforations  to- 
distribute  gas ;  g,  false  bottom ;  A,  cock ;  i,  discharging  man-hole  ;  k, 
steam  pipe  ;  I,  covers  of  pipes ;  m,  receiver  to  hold  the  liquid  pumped 
up  through  n  n,  and  discharged  by  the  perforated  distributor  o  over  the 
entire  surface  of  the  material  in  the  vessel. 

Figs.  15  and  16,  Plan  AB  of  Fig.  14,  same  reference  letters. 

Claims.  1st.  I  claim  the  method  of  mixing  the  aforesaid  auriferous 
substances  with  the  solvent  materials  herein  before  mentioned  by  means 
of  a  puddling  machine  and  pug  mill,  or  other  contrivance  of  a  similar 


nature  as  herein  before  mentioned.  I  claim  the  method  of  keeping  up 
the  strength  of  the  solution  of  chlorine  in  vessels  of  any  shape  contain- 
ing the  auriferous  substances  under  process  by  forcing  in  chlorine  gas 
from  a  retort  or  other  contrivance  by  means  of  a  gasometer,  force  pump, 
bellows,  or  other  contrivance  (see  Hears  subsequently),  to  be  composed 
of  materials  not  acted  upon  by  chlorine,  substantially  as  herein  before 
described.  And  I  claim  the  method  of  agitating  the  auriferous  sub- 
stances during  the  process  by  means  of  an  agitator  (Cobley  and  Wright 
previously),  such  as  shown  by  the  accompanying  drawings,  or  of  any 
other  shape,  and  the  reduction  by  evaporation  of  the  gold  solution  in 
shallow  vessels  or  other  contrivances  previously  to  precipitation 
(Duflos,  Lange,  and  Cobley  and  Wright  previously}.  I  claim  the  appa- 
ratus as  herein  before  described  and  shown  in  the  accompanying 
drawings. 


Remedies.  127 

2nd.  I  claim  the  method  of  obtaining  chlorine  by  heating  metallic 
chlorides,  preferring  those  of  copper,  in  suitable  vessels  or  retorts  as- 
herein  before  described.  Also  the  method  of  generating  chlorine  from 
common  salt,  sulphuric  acid,  and  chromates,  as  herein  before  described, 
and  the  mixing  of  the  aforesaid  materials  for  the  production  of  chlorine- 
with  auriferous  substances  in  close  vessels  under  pressure,  and  the 
application  of  heat,  by  steam  or  in  other  manner  as  herein  before  des- 
cribed. 

One  of  the  chief  reasons  which  prevented  the  general 
adoption  of  this  process  in  Australia  was  the  mechanical 
difficulties  connected  with  its  working.  No  joints  could 
be  kept  tight,  so  the  men  were  continually  in  an  atmo- 
sphere of  chlorine.  The  hollow  trunnion  to  the  barrel 
through  which  gas  was  forced  was  an  especial  weakness. 
With  such  a  highly  corrosive  gas  as  chlorine,  that 
attacks  and  decomposes  all  suitable  materials  in  common 
use,  with  the  exception  of  glass  and  earthenware,  it  is 
of  little  wonder  that  failure  speedily  resulted,  owing  to 
the  unnecessary  generator,  gasometer,  joints,  taps,  &c., 
from  all  of  which  gas  escaped  in  daily  increasing  quan- 
tities. The  process  eventually  went  the  way  of  all  other 
partially  perfected  inventions — it  drifted  into  obscurity 
and  was  forgotten  ;  only  by  old  mining  men  and  personal 
acquaintances  of  the  inventor  was  it  known  to  have 
existed,  when  further  developments  a  short  time  back 
caused  its  principles  to  be  again  discussed. 

CALVERT,  1864. 

At  a  meeting  of  the  British  Association  held  in  Bath 
in  the  year  1864,  F.  Crace  Calvert,  F.E.S.,  read  a  paper 
making  suggestions  for  a  method  of  chlorination  of  gold 
ores.^  The  practice  advocated  by  Mr.  Calvert  was  the 
generation  of  nascent  chlorine  inside  the  ore  mass,  which 
was  to  be  put  into  closed  vats ;  after  sufficient  time  had 

*  Mining  and  Smelting  Mag.,  vol.  vi.,  p.  267. 


128  Remedies. 

elapsed  water  was  to  be  introduced  into  the  vat  on  top 
of  the  ore  ;  when  this  had  percolated  through  it  was  to 
be  again  poured  over  the  top  of  the  ore,  and  so  on  for 
several  times.  After  all  the  gold  had  been  dissolved  out 
of  the  ore,  the  liquor  was  to  be  heated  to  drive  off  the 
free  chlorine. 

PHILLIPS,  1871. 

In  Mr.  J.  S.  Philips'  "  Metallurgists'  Companion,"  the 
1st  edition  of  which  was  published  in  San  Francisco  in 
1875,  appears  the  following  : 

Chlorinize  for  gold  in  revolving  wood  barrels  instead  of  in  tubs, 
draw  off  the  chloride  of  gold 'liquor  for  precipitation,  then  finish  for 
extraction  of  silver  by  amalgamation.  I  suggest  this  for  trial,  as  it 
appears  a  better  and  quicker  method  for  even  the  chlorination  of  gold, 
and  which  also  amalgamates  the  silver.  The  barrel  is  the  most  efficient 
almalgamator,  and  there  is  no  reason  why  it  will  not  chlorinize  better 
and  much  faster  than  tubs.  Two  revolving  barrels  may  be  used,  the 
one  large  for  the  moistened  roasted  ore,  the  other  of  suitable  size  for 
holding  the  materials  for  formation  of  the  gas  ;  they  may  be  made  to 
communicate  through  a  hollow  axle,  and  be  supplied  with  ore  and 
discharged  through  individual  bung-holes,  or  be  so  arranged  that  one 
gas  generator  shall  supply  the  whole  of  the  barrels,  by  tubes  through 
each  axle  or  bung-hole. 

DAHNE,  1874. 

In  the  United  States  patent  records  the  following 
specification  appears,  excerpts  of  which  are  given.  No. 
159,647  filed  November  27th,  1874  : 

.  .  .  .  I,  F.  W.  Dahne,  of  South  Wales,  in  the  kingdom  of  Great 
Britain,  \7ice-Consul  of  the  German  Empire,  have  invented  a  new  and 
improved  process  for  extraction  for  gold  ....  and .  consists  in  the 
employment  of  liquid  (1)  chlorine  (by  which  term  I  mean  an  aqueous 
solution  of  chlorine,  which  I  have  obtained  in  practice  by  dissolving  (2) 
chloride  of  lime  in  water)  and  hydrochloric  acid,  as  a  solving  reagent. 
....  The  supernatant  liquor,  after  the  mixture  has  been  allowed  to 
settle,  is  then  decanted  off  into  a  suitable  vessel,  and  boiled  by  steam 
to  expel  any  excess  of  chlorine  (Henderson,  De  Lacy,  C 'divert,  and  others, 


Remedies.  129 

previously ;  Hears  subsequently)  ....  Claim  :  The  described  process 
of  extracting  gold  consisting  essentially  in  the  treatment  of  auriferous 
material,  with  an  aqueous  solution  of  chloride  of  lime  and  hydrochloric 
acid  (Diiflos,  Lange,  Cobley  and  Wright,  and  De  Lacy,  previously),  and 
precipitating  the  gold  from  the  solutions  thus  obtained  by  sulphurous 
acid,  substantially  as  described. 

(1.)  There  is  no  such  chemical  as  liquid  chlorine  except 
that  produced  by  the  compression  of  chlorine  gas. 

(2.)  An  aqueous  solution  of  chloride  of  lime,  with  the 
proper  combining  chemicals,  would  evolve  chlorine  gas, 
which  would  act  upon  the  gold  exactly  in  the  same 
manner  as  applied  by  every  other  worker  in  the  subject 
(see  Cobley  and  Wright,  De  Lacy,  and  others).  The 
criticisms  on  the  previous  specification  referred  to  are 
applicable  to  this  "  invention." 

COBLEY,  1875. 

United  States  patent,  No.  174,118,  filed  October  21st, 
1875,  was  granted  to  Thomas  Henry  Cobley,  of  Glasgow, 
North  Britain,  for  : 

Improvements  in  obtaining  gold  from  auriferous  quartz,  &c 

My  invention  relates  to  the  process  of  obtaining  gold  by  chlorination 
and  precipitation,  &c. 

This  inventor  steeps  the  ore  previous  to  roasting  in 
milk  of  lime  (whitewash),  then  crushes  it  in  some 
machine,  wherein  it  "  does  not  come  into  contact  with 
metallic  iron  ; "  it  is  then  placed  in  a  vat  which  "  should 
not  be  constructed  of  wood  or  metal,"  into  which  chlorine 
is  subsequently  added ;  and  while  the  gold  is  in  the  form 
of  a  chloride,  "  it  is  essential  that  contact  between  it  and 
other  metals  or  organic  matter  should  be  carefully 
avoided  ;"  the  steam  jet  arrangement  so  frequently  men- 
tioned by  "  inventors  "  is  then  turned  on.  The  leachings 
from  the  chlorinating  vat  are  then  to  run  through  a 
filter  of  quartz  sand,  and  the  gold  in  this  filtered  solution 


130  Remedies. 

returned  to  metal  by  the  aid  of  sulphuretted  hydrogen  ; 
the  liquor  containing  the  metallic  gold  is  run  through  a 
sawdust  filter  where  it  is  caught,  and  the  sawdust  subse- 
quently burned  and  the  metallic  gold  obtained.  The 
claims  of  the  patent  are  as  follows  : 

The  process  described  of  obtaining  gold  from  auriferous  quartz,  by 
first  steeping  the  ore  in  milk  of  lime ;  second,  roasting  it ;  third,  pul- 
verizing it ;  fourth,  subjecting  it  to  the  action  of  heat  and  chlorine  in  a 
stone  vat;  and,  fifth,  washing  and  filtering  the  chloride  of  gold  as 
described,  the  chloride  being  then  reduced  in  the  ordinary  manner. 

The  inventor  has  omitted  to  state  the  object  to  be 
gained  by  steeping  the  ore  in  whitewash — to  the  non- 
inventive  mind  the  reason  is  certainly  obscure.  None  of 
the  other  claims  could  be  for  a  moment  sustained,  and 
are  only  complications  of  what  has  been  done  by  others 
long  before  in  a  simpler,  and  certainly  more  economical, 
manner. 

MEARS,  1877. 

On  the  30th  July,  1877,  J.  J.  Howell  Mears,  M.D., 
of  Philadelphia,  filed  in  the  United  States,  patent  speci- 
ficatioh  No.  195,381,  relating  to  an  invention  for  treating 
gold  ores  by  chlorination.  Three  subsequent  specifi 
cations  or  reissues  were  filed,  No.  8,859  on  the  31st 
January,  1879;  No.  9,203  on  the  16th  March,  1880; 
and  No.  269,441  on  the  6th  August,  1880.  These 
specifications  arid  reissues  will  be  referred  to  as  Nos. 
1,  2,  3,  and  4,  in  the  order  of  their  dates,  when  excerpts 
are  given  or  their  provisions  discussed.  These  succeed- 
ing specifications  repeat  so  frequently,  that  it  would  be 
wearisome  to  give  in  each  instance  similar  excerpts ; 
material  points,  or  those  where  different  expression 
might  warrant  a  different  construction,  will  alone  be 
quoted. 


Remedies.  131 

No.  1,  1877  (no  drawings).     Excerpts  are  as  follows  : 

The  nature  of  my  invention  consists  in  treating  ores  by  means  of 
chlorine  gas  evolved  within  the  ore  under  pressure  while  in  a  state 
of  agitation  (see  De  Lacy  and  Phillips  previously,  also  Cobley  and 
Wright's  practice).  In  carrying  out  my  invention  I  proceed  as  follows  : 
The  ore  is  properly  roasted  and  pulverized — the  finer  the  better — and 
introduced  into  a  tank  with  about  one-half  its  weight  of  water,  into 
which  is  staked  a  proper  proportion  of  lime — ordinary  lime  of  com- 
merce— the  whole  being  then  thoroughly  incorporated  by  rotating 
the  tank  (Duflos  and  De  Lacy,  previously).  Chlorine  gas  is  now  intro- 
duced into  the  mass,  and  the  tank  kept  in  motion  (DeLacy)  until  no 
more  gas  will  be  absorbed,  which  can  be  determined  by  a  suitable 
device  for  the  purpose.  The  rotation  of  the  tank  is  then  discontinued ; 
dilute  sulphuric  acid  is  added  to  the  mixture  (De  Lacy),  and  the  tank 
is  again  rotated  for  half  and  hour,  when  the  chlorination  is  complete  (1). 
....  After  effervescence  has  ceased,  almost  all  the  gas  has  passed  off 
into  the  second  tank  ;  hot  water  is  introduced  into  the  first  tank  until 
the  temperature  of  the  mass  reaches  about  160  deg.  or  200  deg.,  when 
all  the  free  chlorine  will  have  been  expelled  (see  practice  of  Henderson, 
Cobley  and  Wright,  DeLacy,  Calvert,  Dahne,  and  Cobley,  previously). 
....  The  shaft  on  which  the  tank  revolves  will  be  hollow,  so  that  the 
chlorine  may  be  admitted  into  the  tank  while  the  latter  is  in  motion 
(DeLacy).  The  inner  face  of  the  tank  will  be  provided  with  cleats 
secured  thereto  at  intervals,  so  as  to  facilitate  the  stirring  or  agitation 
of  the  mass  (De  Lacy) 

Claims  :  In  treating  the  ores  the  process  of  chlorination  consisting 
in  mixing  the  ore  with  lime  and  water  in  air-tight  tanks,  introducing 
chlorine  gas  thereinto  while  in  a  state  of  agitation,  then  adding  acid, 
and  again  agitating  the  mass,  whereby  chlorine  gas  is  evolved  in  the 
mass  of  ore  under  pressure,  substantially  as  and  for  the  purpose  set 
forth. 

(1.)  The  putting  of  lime  in  the  barrel,  mixing  with 
the  ore,  and  then  forcing  in  chlorine  gas,  is  simply  a  method 
of  making  chloride  of  lime  :  half  the  time  of  the  process 
would  be  thus  occupied.  De  Lacy  mixed  his  chloride 
of  lime  and  ore  in  a  pug  mill,  then  transferred  them  to 
the  barrel,  and  by  adding  dilute  sulphuric  acid,  was 
enabled  to  conduct  the  process  without  the  preliminary 
trouble  of  forcing  chlorine  gas  through  a  hollow  axle  and 


132  Remedies. 

the  disadvantage  of  losing  at  the  least  one  equivalent 
of  chlorine  in  the  formation  of  chloride  of  calcium. 

No.  2,  1879  (no  drawings).  Excerpts  from  this  patent 
are  as  follows  : 

I  am  further  aware  that  it  is  not  new  to  dissolve  the  gold  in  the 
form  of  chloride  by  treating  the  ore  with  hypochlorite  of  lime  and 
hydrochloric  acid,  then  removing  the  excess  of  chlorine  by  steam  and 
precipitating  the  gold  by  sulphuric  acid ;  wherefore  I  disclaim  such 
features. 

Having  thus  fully  described  my  invention,  I  hereby  disclaim  all 
the  well-known  processes,  chemical  and  mechanical,  which  enter  into 
the  said  description  (2) :  but  what  I  do  claim  and  desire  to  secure  by 
letters  patent  is  : 

In  treating  ores,  the  process  of  chlorination  consisting  in  subjecting 
the  ore,  mixed  with  water  in  a  strong  air-tight  vessel  while  in  a  state 
of  agitation,  to  chlorine  gas  under  a  greater  pressure  than  that  of  the 
atmospheric  pressure,  by  generating  chlorine  gas  in  said  vessel  or  tank 
by  chemical  means,  so  as  to  produce  the  pressure  for  the  purpose  of 
extracting  the  precious  metals,  in  combination  .as  chlorides  in  solution, 
substantially  as  and  for  the  purpose  set  forth  (3). 

(2.)  This  disclaimer  practically  covers  every  point  in 
the  patent. 

(3.)  These  claims  have  been  so  completely  covered  by 
previous  patents  years  before  ;  individual  references  are 
bracketed  when  dealing  with  No  1,  so  that  it  is  needless 
to  give  the  same  references  over  again. 

No.  3,  1880  (no  drawings).  Excerpts  from  this  patent 
are  as  follows : 

My  invention  consists  in  a  process  of  chlorinating  ores  by  charging 
them  (4)  with  chlorine  gas  under  a  pressure  greater  than  that  of  the 
atmosphere  (De  Lacy's  second  method),  so  that  a  concentrated  solution 
of  chlorine  is  obtained,  and  is  made  to  act  upon  the  ore  with  superior 
efficiency  as  compared  with  the  older  method  of  charging  under  atmo 
spheric  pressure  only  ;  secondly,  in  the  said  process,  when  the  super 
atmospheric  pressure  is  produced  by  the  evolution  of  chlorine  gas 
within  a  closed  chamber  containing  the  ore  (5) ;  and,  thirdly,  the  first- 
named  process,  when  the  contents  of  the  vessel  are  kept  in  agitation 
during  the  process  of  chlorination  (6)  .  .  .  .  continuous  rotation  during 


Remedies.  133 

chlorination  has  the  effect  of  expediting  and  facilitating  the  chemical 
reactions  involved  (Cobley  and  Wright,  De  Lacy,  and  Phillips).    I  claim: 

1.  The  process  of  chlorinating  ores,  which  consists  in  charging  the 
ore  with  chlorine  under  a  pressure  greater  than  that  of  the  atmosphere, 
whereby   the   union    of  the   chlorine   with    the   metal    of   the   ore   is 
facilitated,  substantially  as  set  forth. 

2.  The  process  of  chlorinating  ores,  which  consists  in  charging  the 
ore  with  chlorine  under  a  pressure  greater  than  that  of  the  atmosphere, 
such  pressure  being  produced  by  the  evolution  of  chlorine  gas  within  a 
closed  chamber  containing  the  ore,  substantially  as  described. 

3.  The  process  of  chlorinating  ores,  which  consists  in  charging  the 
ore  with  chlorine  nnder  a  greater  pressure  than  that  of  the  atmosphere, 
and  keeping  the  contents  of  the  vessel  in  agitation  during  the  process 
of  chlorination,  substantially  as  described. 

(4.)  The  patentee  here  evidently  abandons  the  chloride 
of  lime  factory  inside  the  barrel.  The  process  then 
resolves  itself  into  De  Lacy's  alternative  method.  In 
claim  No..  2,  the  older  method,  though  retained,  is  put 
second  on  the  list. 

(5.)  Super  atmospheric  pressure  was  attained  by  Cobley 
and  Wright  when  they  generated  chlorine  from  chemicals 
mixed  with  the  ore.  De  Lacy  lays  special  stress  on  this 
point. 

(6.)  Cobley  and  Wright  must  have  agitated  in  a 
closed  vessel,  for  an  open  one  would  have  been  unwork- 
able. De  Lacy  agitated  in  a  closed  vessel  by  agitators, 
.and  also  in  a  rotating  barrel. 

No.  4,  1880  (drawing  reproduced,  Fig.  17).  This  is 
the  last  specification  of  this  patentee.  Excerpts  are  as 
follows : 

My  improvement  consists,  first,  in  performing  the  operation  of 
charging  the  ore  with  chlorine  gas  in  a  close  air-tight  vessel,  from  which 
the  atmospheric  air  has  previously  been  exhausted  (Toussaint  and 
Langlois,  previously),  in  then  forcing  in  the  chlorine  gas,  so  that  it  shall 
be  under  super  atmospheric  pressure  while  charging  and  acting  upon 
the  ore  while  undiluted  (De  Lacy),  and  in  agitating  the  contents  of  the 
chlorinator  during  the  process-  of  charging  the  ore,  and  while  the  gas  is 


134 


Remedies. 


acting  upon  it  (De  Lacy) ;  and,  secondly,  in  the  combination  of  a  recep- 
tacle adapted  to  contain  a  supply  of  chlorine  under  super  atmospheric 
pressure  (De  Lacy),  a  chlorinator  adapted  to  resist  pressure  and  to 
agitate  its  contents  during  the  introduction  of  the  gas  (De  Lacy\  and 
an  apparatus  for  exhausting  the  chlorinator  (Toussaint  and  Langlois], 
all  suitably  connected  and  combined  as  hereinafter  described.  The 
accompanying  drawing  represents  an  arrangement  of  apparatus  shown 
in  vertical  longtitudinal  section,  suitable  for  carrying  out  my  invention. 
a  is  a  generator  or  retort  in  which  the  chlorine  gas  is  produced. 
This  vessel  is  preferably  constructed  of  sheet  lead. 


•;::.£?::; 


The  usual  process  of  generating  the  gas  consists  in  placing  within  the 
vessel  a  quantity  of  pulverized  peroxide  of  manganese,  common  salt, 
and  water.  The  cover  is  then  secured,  and  a  quantity  of  sulphuric  acid 
introduced  through  the  bent  leaden  pipe  «',  which  is  formed  into  a  funnel 
shape  at  its  outer  end.  The  chlorine  gas  generated  by  the  action  of 
the  ingredients  passes  through  another  leaden  pipe  b,  which  leads  to  a 
purifying  apparatus  which  .may  consist  of  a  wash-bottle  c — in  passing 
through  which  the  gas  is  forced  through  a  body  of  water,  which  takes 
up  the  muriatic  acid  contained  in  it.  The  chlorine  then  passes  by  a 
pipe  c,  provided  with  a  stop  valve  c  into  a  balance  gas  holder  d,  which 
may  be  of  any  suitable  or  well-known  construction,  and  serves  to  con- 
tain a  quantity  of  gas  in  a  condition  ready  for  use,  as  required. 


Remedies.  135 

h  is  an  air  pump  of  ordinary  construction  go  arranged  as  to  be 
capable  of  drawing  the  gas  from  the  gas  holder  through  the  pipe  d,  k, 
and  forcing  it  into  the  receptacle/  through  the  pipe  k'.  The  vessel 
or  receptacle  /should  be  made  strong  to  withstand  any  pressure  of  gas 
that  may  be  required  in  the  operation  about  to  be  described — say  40  Ib, 
or  50  Ib.  to  the  square  inch,  or  as  much  more  as  may  be*  found  conve- 
nient or  advisable. 

e  represents  a  section  of  the  treating  vessel — sometimes  termed  a 
"  chlorinator " — which  is  preferably  constructed  of  a  cylindrical  or 
barrel  shape,  and  is  mounted  on  trunnions  e  e  and  driven  by  the  pulley 
k.  The  trunnion  e  is  hollow  and  through  it  passes  the  pipe  with  its 
goose-neck /into  the  open  space  above  the  charge  o  o  o.  The  chlorinator 
e  is  connected  with  the  receptacle  /  by  the  goose-neck  /  and  the  pipes 
li  i  or,  through  the  pump  h,  to  the  pump  h  by  the  goose-neck  /  and 
the  pipes  h  d  or  through  the  pump  h. 

i  is  the  exhaust  apparatus  which  may  be  a  steam  jet,  a  pump,  a  water 
column,  or  any  other  suitable  contrivance.  It  is  connected  with  the 
chlorinator  e  by  the  pipe  I  and  the  goose-neck  y,  and  to  the  receptacle 
/"by  the  pipes  £,  h',  i. 

nnnnn  are  cocks  or  valves  to  connect  or  disconnect  the  different 
parts  of  the  apparatus. 

g  and  g'  are  pressure  and  exhaust  gages. 

I  am  aware  that  various  processes  are  described  in  publications  prior 
to  this  application  for  the  extraction  of  gold  from  its  ores  by  the  agency 
of  chlorine  gas,  in  which  several  of  the  steps  of  my  process  were  em- 
ployed in  connection  with  other  agencies.  My  process  is  an  improve- 
ment upon  these,  in  that  it  unites  the  three  steps — vacuum,  pressure 
and  agitation — in  the  one  operation,  thereby  producting  a  new  result  ; 
and  further,  in  that  it  dispenses  with  the  use  of  steam,  and  of  heating 
agencies  deemed  essential  in  the  old  processes  that  employed  pressure, 
and  thereby  again  producting  a  new  result. 

My  process  requires  and  uses  no  heat,  requires  and  uses  no  steam, 
does  not  generate  the  chlorine  in  presence  of  the  ore,  and  accomplishes 
a  new  result  in  the  saving  of  time,  and  the  thoroughness  of  the  extrac- 
tion of  the  gold. 

I  do  not  herein  claim  what  has  been  secured  to  me  in  a  prior  patent, 
of  date  September  18,  1887,  and  numbered  195,381,  and  the  re-issues 
thereof ;  but  what  1  do  claim,  and  desire  to  secure  by  letters  patent,  is : 
1.  The  process  of  chlorinating  ores  which  consist  in  exhausting  the 
chlorinator  containing  the  ore,  then  forcing  in  chlorine  gas  so  that  such 
gas  shall  be  under  superatmospheric  pressure  while  acting  upon  the  ore 
and  agitating  the  contents  of  the  chlorinator  during  the  process,  sub- 
stantially as  and  for  the  purpose  described. 


136  Remedies. 

2.  The  combination  substantially  as  herein  before  set  forth,  of  a  re- 
ceptacle constructed  as  described,  whereby  it  may  contain  a  supply  of 
chlorine  under  super-atmospheric  pressure  ;  a  chlorinator  constructed  as 
described,  whereby  it  may  resist  pressure  and  agitate  its  contents ;  and 
connections  as  described. 

3.  The  combination,  substantially  as  herein  before  set  forth,  of  a  re- 
ceptacle constructed  as  described,  whereby  it  may  contain  a  supply  of 
chlorine  under  super-atmospheric  pressure ;  a  chlorinator  constructed  as 
described,  whereby  it  may  resist  pressure  and  agitate  its  contents  ;  an 
apparatus  for  exhausting  the  said  chlorinator,   and  connections  as  de- 
scribed. 

4.  The  combination,  substantially  as  herein  before  set  forth,  of  the 
generator  a,  the  holder  d,  the  pump  A,  the  reservoir  /,  the    exhaust  i, 
the  chlorinator  e,  the  goose-neck/,  and  connections  as  described. 

5.  The  combination,  substantially  as  herein  before  set  forth,  of  the 
generator  a,  the  holder  d,  the  pump  h,   the  reservoir  /,  the  chlorinator 
e,  the  goose-neck  y,  and  connections  as  described. 

The  foregoing  is  principally  a  patent  for  the  combina- 
tion of  certain  mechanical  devices,  none  of  which  present 
any  novelty,  the  other  provisions  of  the  specification  are 
more  or  less  generally  covered  by  the  patentee's  previous 
claims.  The  going  back  to  outside  generator,  gasometer, 
or  pressure  tank,  &c.,  so  as  to  force  chlorine  gas  through 
a  hollow  trunnion  and  thereby  obtain  pressure,  was 
certainly  a  retrograde  step.  The  criticism  for  this  speci- 
fication having  been  so  fully  entered  into  by  bracketed 
references,  &c.,  for  those  preceding,  it  would  be  wearisome 
to  the  reader  to  further  reiterate  in  detail  all  the  main 
points  of  the  patent  which  have  been  covered  by  previous 
patents  years  before.  For  the  closing  history  of  this 
process  it  will  be  sufficient  to  say,  that  for  a  few  years 
it  "  boomed "  away  merrily  in  the  United  States,  a 
company  was  formed  for  the  purpose  of  working  the 
patents,  and  great  things  were  predicted  for  them,  appa- 
rently in  ignorance  of  the  failure  in  Australia  some 
fifteen  or  sixteen  years  previously  of  a  process  working 


Remedies. 

on  identically  the  same  lines.  Some  short  time  back 
the  Mears  Company  recalled  their  pamphlets  and  wound 
the  concern  up.  *  Did  the  mechanical  difficulties  which 
proved  fatal  to  the  De  Lacy  process  also  kill  this  later 
effort  in  the  same  direction  ?  or,  as  suggested  by  Mr. 
Stetefeldt,  did  it  die  "  from  sheer  inanity  ?  "f 

SCHAEFFER,     1880. 

In  the  United  States  on  the  28th  June,  1880,  Charles 
A.  Schaeffer  filed  specification  No.  267,723  to  patent 
the  process  of  dissolving  gold  by  aid  of  bromine.  There 
was  no  novelty  in  the  manner  of  applying  the  chemical, 
the  means  suggested  being  the  same  as  in  an  ordinary 
chlorine  process. 

It  seems  strange  that  a  patent  should  be  granted  for 
any  such  method  of  dissolving  gold,  for  in  every  standard 
work  on  chemistry  bromine  is  given  as  one  of  the 
solvents. 

MEARS,   1880. 

This  specification,  No.  269,441,  has  been  already 
mentioned  and  criticised  under  head  No.  4  on  page  130. 

DE  FIGANIERE,  1881. 

Specification  No.  267,842,  filed  on  the  9th  February, 
1881,  by  Mr.  A.  De  Figaniere,  of  Philadelphia,  is  one 
with  which  bromine  is  the  solvent  agent,  used  in  con- 
nection with  a  revolving  apparatus  somewhat  similar  to 
the  methods  ordinarily  employed  for  chlorination.  It 

*  This  on  the  authority  of  a  gentleman  well  known  in  metallurgical 
circles  in  the  United  States. 

t  Mr.  Stetefeldt  in  Trans.  Am.  Inst.  Min.  Eng.,  vol.  xiii.,  page  84  : 
"  Why  is  it,  I  may  ask,  that  we  hear  very  little  about  this  process 
{ Mears'),  so  excellent  on  theoretical  grounds  ?  Have  its  technical  diffi- 
culties been  found  insurmountable,'  or  has  it  died  from  sheer  inanity  ? " 


138  Revnedies. 

would  seem  from  the  granting  of  this  patent  that  the 
United  States  officials  had  some  doubts  as  to  the  stability 
of  Schaeffer's  patent  just  previously  issued. 

EVANS,   1882. 

The  specification  of  Mr.  Nelson  Frederick  Evans,  of 
Philadelphia,  patented  in  Great  Britain  22nd  June, 
1882,  No.  1063,  is  substantially,  though  not  word  for 
word,  the  same  as  the  Mears  United  States  patent 
269,441  ;  but  the  drawing  accompanying  it  is  exactly  the 
same,  just  as  if  both  had  been  printed  from  the  same 
block.  The  claims  in  Evans'  specification  are  : 

1.  The  process  of  chlorinating  ores,  wherein  the  ore  is  charged  with 
chlorine  under  a  pressure  greater  than  that  of  the  atmosphere,  such 
pressure  being  produced   by  the  evolution   of  chlorine  gas  within  a 
closed  chamber  containing  the  ore,  or  otherwise  produced,  substantially 
as  described  and  for  the  purpose  specified. 

2.  The   process  of   chlorinating  ores  and  recovering  the  unused  or 
uncombined  chlorine  gas,  substantially  as  herein  set  forth. 

3.  The  goose-neck  in  combination  with  the  chloriiiator,  and  with  or 
without  the   exhaust  apparatus,  substantially  as  and  for  the  purposes 
set  forth. 

4.  The    combination    of    the    goose-neck    with  the    chlorinator,    the 
exhaust   apparatus,    the  pump  /*,  the  gasometer,   and  the    connecting 
pipes  with  their  valves  or  cocks,  substantially  as  described,  and  for  the 
purposes  set  forth. 

The  remarks  for  this  patent  are  the  same  as  those  for 
the  Mears  patent  already  referred  to. 

MUNKTELL,  1884. 

Henrik  MunktelPs  provisional  specification  is  dated 
8th  December,  1884,  and  the  specification  27th  August, 
1885,  No.  16,135.  The  preamble  and  excerpts  from  the 
specification  are  as  follows  : 

I,  Henrik  Munktell,  of  Falun,  Sweden,  engineer,  do  hereby  declare 
the  nature  of  said  invention  for  "  Improvements  in  the  Process  of 


Remedies.  139 

Extracting  Gold  by  Means  of  Chlorine  from   Auriferous  Ores,   Sand, 
Residues  of  Gold- Washing,  and  the  like  "  to  be 

As  in  most  other  specifications  on  the  subject,  some 
roasting  process  is  mentioned  as  an  essential  preliminary 
to  chlorination.  When  referring  to  crushed  ore  it  is 
stated  : 

The  powder,  however,  should  be  sufficiently  coarse  to  allow  liquids  to 
percolate  through  with  ease. 

Those  who  have  followed  these  pages  will  at  once  see 
that  comment  on  this  point  is  needless,  because  ores  that 
may  be  crushed  without  producing  slimes  and  crushers 
working  without  generating  them  are  both  hypothetical, 
unless  that  the  ore  grains  be  left  in  sizes  so  large  as,  in 
all  probability,  to  encase  the  gold  particles.  It  is  the 
impossibility  to  obtain  the  condition  that  Mr.  Munktell 
requires  that  has  led  to  the  careful  damping  found  neces- 
sary in  the  ordinary  chlorinating  vat.  The  chemicals 
used  in  this  process  for  the  production  of  chlorine  are  of 
the  ordinary  nature,  and,  as  will  be  seen  by  the  reader, 
all  the  "  improvements  "  claimed  by  the  patentee  have 
been  tried  and  abandoned  by  the  old  German  chemists  in 
their  investigations  conducted  during  the  years  1848-9. 
The  description  of  the  method  is  as  follows  (Fig.  18)  : 

a  are  extraction  tanks  of  wood;  b  represent  filtering  bottom  in- 
side the  tanks,  consisting  of  a  layer  of  gravel  or  quartz  spread  on 
perforated  boards  or  plates  of  earthenware  bl  placed  on  the  supports  62; 
c  outlet  cock.  For  measuring  the  requisite  proportions  of  the  solutions 
of  hypochlorite  of  lime,  and  the  acid,  the  tubs  d  and  e  are  placed 
on  the  channels  /  and  g  above  the  tanks.  The  diluted  ready-made 
solutions  of  hypochlorite  of  lime  and  acid  are  led  separately  through 
the  channels  h  and  i  into  the  respective  tubs  d  and  e.  As  each  tub 
is  filled  the  plug  k  is  inserted  into  the  hole  in  the  channel  leading  to 
that  tub. 

The  charm  els /are  used  for  admitting  such  acids  and  salt  solutions 
as  are  required  for  dissolving  other  substances  than  gold.  I  are  water 
pipes. 


140 


Remedies. 


After  the  tubs  have  been  filled  the  process  is  commenced  by  remov- 
ing the  plugs  m  and  the  diluted. solutions  of  hypochlorite  of  lime  and 
acid  are  allowed  to  run  in  definite  quantities  out  of  the  tubs  d  and  e 
into  the  channels  g,  meeting  each  other  at  the  openings  n  and  thus 
running  down  together  into  the  material  in  the  tanks. 

By  cross  boards  o  in  the  channels  the  tanks  which  are  not  to  be 
operated  upon  can  be  shut  off.  p  are  channels  to  discharge  the 
solutions  which  are  running  off  or  are  let  out  from  the  tanks  a.  By 
means  of  short  shoots  placed  under  the  cocks  c  the  liquid  is  led  into  the 
respective  channels  p. 

Having  now  particularly  described  and  ascertained  the  nature  of  my 
said  invention  and  in  what  manner  the  same  is  to  be  performed,  I 
declare  that  what  I  claim  is 

In  extracting  gold  by  means  of  chlorine  from  auriferous  ores,   &c., 


free  or  freed  from  sulphur,  causing  a  mixture  of  a  diluted  acid  with  a 
diluted  solution  of  hypochlorite  of  lime  or  some  other  chlorine  generating 
salt  (together  if  necessary  with  chloride  of  sodium  or  some  other  sub- 
stance by  which  chloride  of  silver  is  dissolved)  to  pass  through  the 
crushed  materials,  these  being  freed  from  protoxides  and  kept  in  open 
tanks,  and  the  passing  through  of  the  said  mixture  being  continued  so 
long  as  any  traces  of  gold  (worth  recovery)  are  to  be  found  in  the  solu- 
tions running  off,  substantially  as  described. 

From  the  description  and  the  drawings  it  may  be 
gathered  that  it  is  proposed  to  place  in  each  barrel  one 
of  the  solutions  which  produce  chlorine,  in  the  same 
manner  as  seidlitz  powders,  in  blue  and  white  papers,  may 
be  mixed  in  separate  glasses.  The  liquids  are  then  run 


Remedies.  141 

from  opposite  directions  down  an  open  shoot,  where  they 
are  supposed  to  meet  and  mix  over  a  hole  n.  When  these 
liquids  meet  they  evolve  chlorine  gas  much  in  the  same 
way  and  at  about  the  same  speed  that  the  liquids  of 
seidlitz  powders  evolve  carbonic  acid  gas.  Chlorine  gas 
is  the  solvent  agent  for  gold  ;  it  would  be  in  a  nascent 
state  before  it  reached  the  ore,  and  much  of  it  must 
escape,  and  to  use  the  patentee's  own  words  when  re- 
ferring to  alternative  method  : 

In  this  case,  however,  not  only  does  much  chlorine  escape  which  has 
a  very  detrimental  effect  on  the  carrying  out  of  the  process,  but  also 
larger  quantities  of  the  solutions  are  required. 

Such  really  would  be  the  state  of  affairs,  except  with 
very  dilute  solutions,  and  the  more  dilute  the  solution 
the  greater  length  of  time  would  be  occupied  in  treating 
the  charge.  In  the  "  Plattner  "  vat,  where  a  lid  is  luted 
on  and  every  precaution  taken  to  keep  up  the  strength 
of  the  gas  and  prevent  escape,  the  process  occupies  about 
three  days.  With  the  Munktell  process  working  with 
dilute  solutions  (even  allowing  for  a  supposititious  case  of 
all  other  conditions  being  highly  favourable),  the  time 
occupied  to  bring  about  a  result,  must  of  necessity  exceed 
very  greatly  that  of  the  old  "  Plattner  "  process. 

Other  points  are  these  :  the  solution  pours  over  the 
ore  in  the  vat.  In  the  majority  of  cases  it  would  at  once 
form  a  clogging  mixture  with  the  finer  particles  of  ore, 
which  would  prevent  its  percolation  through  the  mass 
(see  Lange,  1849)  ;  then  it  would  fizzle  away  on  the  sur- 
face, evolving  gas  until  exhausted,  would  not  dissolve  the 
gold,  and  would  drive  every  one  out  of  the  shed.  If  the 
ore  was  of  the  size  and  nature  that  the  solution  could 
percolate  through  it,  all  the  ore  could  not  be  wetted  with 
the  apparatus  described,  until  the  solutions  had  so  filled 


142  Remedies. 

the  vat  that  the  ore  was  awash  ;  then  the  same  escape  of. 
chlorine  gas  would  take  place  as  the  case  where  the 
solution  could  not  percolate.  Looking  at  the  patent  from 
every  point,  and  allowing  for  the  most  favourable  condi- 
tions, it  resolves  itself  into  a  "  Plattner  "  vat,  without  the 
lid,  without  any  provision  to  prevent  escaping  gas,  and 
with  all  the  disadvantages  of  the  "  Plattner "  process 
without  any  of  its  advantages. 

HARGREAVES  AND  OTHERS,  1886. 

The  specification  of  James  Hargreaves,  Thomas  Robin- 
son, and  John  Hargreaves,  No.  5681,  applied  for  on  April 
27th,  1886,  accepted  on  March  8th,  1887  : 

Relates  to  improvements  in  the  treatment  of  pyrites  for  the  purpose 
of  obtaining  the  sulphur  and  valuable  metals  therein  contained,  and  in 
apparatus  employed  therein. 

There  are  twenty-two  claims  in  this  specification,  but 
all,  with  the  exception  of  two,  refer  to  furnaces  and  other 
subjects  not  directly  concerning  this  inquiry.  The  chief 
feature  in  this  process  is  the  use  of  dry  chlorine,  applied 
as  follows  : 

We  pass  the  acid  gases  through  the  pyrites  at  a  temperature  below 
chat  at  which  the  salts  of  the  valuable  metals  are  largely  volatilized  or 
the  copper  salts  reduced,  and  when  the  pyrites  contain  gold  after  being 
treated  with  acid  gases  we  cool  the  pyrites  to  below  400  deg.  Fahr.,  if 
not  already  below  that  temperature,  and  maintain  the  said  pyrites  in  an 
atmosphere  of  chlorine. 

There  seems  to  be  no  reason  why  this  method  should 
not  be  successful,  but  it  does  not  appear  that  it  has  yet 
been  put  into  practice  on  any  extended  scale,  and  novelty 
cannot  be  claimed,  for  in  the  old  text-book  of  the  early 
part  of  this  century,  hot  chlorine  gas  is  advocated  as  a 
method  for  separating  metals,  amongst  others  the  base 
metals  from  gold.  Its  applicability  will  be  entirely  ruled 


Remedies.  143 

by  economical  considerations  as  compared  with  wet 
methods,  for  in  the  matter  of  acsuracy  the  latter  have 
almost  reached  perfection. 

There  are  no  drawings  with  the  specification.  The 
claims  referring  to  the  portion  under  notice  are  as  below: 

16.  Rendering  soluble  the  valuable  metals  contained  in  pyrites  by 
means  of  acid  gases  as  herein  described,  subsequently  washing  out  the 
said  valuable  metals  so  rendered  soluble,  in  a  series  of  tanks,  substan- 
tially as  described. 

17.  Obtaining  an  increased  quantity  of  soluble  gold  from  pyrites  by 
first  passing  acid  gases  through  or  amongst  the  mass  and  afterwards 
maintaining  the  pyrites  in  an  atmosphere  of  chlorine  at  a  temperature 
of  not  more  than  400  deg.  Fahr.,  substantially  as  described. 

Me  ARTHUR  AND  OTHERS,  1886. 

The  specification  of  John  Stewart  McArthur,  Robert 
Wardrop  Forrest,  William  Forrest,  and  George  Morton, 
No.  11,817,  applied  for  on  September  17th,  1886, 
accepted  July  15th,  1887  : 

Has  principally  for  its  object  the  obtaining  of  gold,  from  ores  or  other 
compounds,  but  it  is  also  applicable  for  obtaining  silver  and  other  noble 
metals  from  such  compounds;  and  it  comprises  an  improved  process 
which,  whilst  applicable  to  various  ores  and  compounds,  is  effectual 
with  ores  or  compounds  from  which  gold  or  other  noble  metals  have 
hitherto  not  been  easily  obtainable. 

What  we  claim  is  : 

The  improved  process  for  obtaining  gold,  silver,  and  other  noble 
metals  from  ores  or  compounds,  and  consisting  in  treating  the  ores  or 
compounds  in  a  powdered  condition  with  chlorine,  bromine,  or  iodine, 
in  a  solution  also  containing  salts,  such  as  those  hereinbefore  specified, 
which  will  not  to  any  material  extent  absorb  the  chlorine,  bromine,  or 
iodine,  nor  precipitate  gold  from  solution,  but  will  prevent  base  metals 
and  pyrites  or  mundic  from  dissolving,  the  process  being  conducted  sub- 
stantially as  hereinbefore  described. 

The  patent  is,  in  effect,  a  sort  of  roving  commission  to 
mix  pyrites  with  carbonates,  borax,  silicates,  sulphuric 
acid,  chloride  of  lime,  &c. ;  in  the  provisional  specification 


1 44  Remedies. 

glycerine  and  alcohol  were  also  mentioned,  with  a  final 
statement,  that  it  would  be  better  to  conduct  the  opera- 
tion in  darkness.  These  latter  portions  the  patentees 
have  omitted  from  their  last  specification,  having  evi- 
dently come  to  the  conclusion  that  the  light  of  day  was 
necessary  for  the  execution  of  such  a  complicated  pur- 
pose. 

HANNAY,  1886. 

The  specification  of  James  Ballantyne  Hannay,  No. 
14,061,  applied  for  on  November  2nd,  1886,  accepted  on 
August  23rd,  1887  : 

Has  for  its  object  to  improve  and  render  more  effective,  economical 
and  satisfactory,  processes  of  the  kinds  in  which  chlorine  is  employed 
for  obtaining  gold  from  refractory  ores  or  other  auriferous  substances. 

In  carrying  out  my  invention  I  employ  liquefied  chlorine,  that  is 
gaseous  chlorine  reduced  to  the  liquid  state  by  well  known  means ;  or  I 
employ  nascent  chlorine  evolved  by  electrolysis  as  in  what  is  known  as 
the  Cassel  process.  The  gold  ore  or  auriferous  substance  is  reduced  to 
a  fine  powder  and  mixed  with  water  or  a  suitable  solution  ;  and  the 
chlorine  is  injected  into  the  mixture  by  means  of  its  own  expansive 

force.  (1) An  important  part  of  my  invention  consists  in 

the  means  which  I  employ  to  avoid  this  premature  precipitation  of  the 

gold And  in  order  to  prevent  the  premature  precipitation 

of  the  gold  by  protosalts  of  iron  or  other  metal ;  (2)  I  dissolve  in  the 
water  or  solution  in  the  compartment  containing  the  cathodes  a  suit- 
able quantity  of  cyanide  of  potassium  or  other  suitable  soluble  cyanide 
or  sulphocyanide,  such  cyanide  having  the  effect  of  keeping  the  gold  in 
solution  until  it  is  by  the  action  of  the  electric  current  carried  to  and 
deposited  upon  the  cathode  or  cathodes What  I  claim  is  : 

1.  Using  liquefied    chlorine  substantially  in  the  manner  hereinbefore 
described  for  obtaining  gold  from  refractory  ores  or  other  auriferous  sub- 
stances. 

2.  Using  cyanide  of  potassium  or  other  suitable  soluble  cyanide  or 
sulphocyanide  in  combination  with  an  electric  current  substantially  as 
and  for  the  purposes  hereinbefore  described. 

(1.)  The  use  of  liquid  chlorine  has  been  previously 
claimed  by  Dahne,  and  his  application  of  the  word  is 
equally  as  erroneous  as  when  used  in  this  patent. 


Remedies.  145 

'Chlorine  is  liquefied  by  a  pressure  of  about  four  atmo- 
spheres, and  the  moment  such  pressure  is  relieved  the 
liquid  at  once  resolves  itself  into  gas.  Mr.  Hannay,  by 
taking  advantage  of  this  "  expansive  force,55  applies 
chlorine  to  ores,  in  a  shorter  time  than  by  some,  but  in 
exactly  the  same  manner  as  it  had  been  applied  by  every 
worker  for  thirty-six  years  previously.  The  object  of 
this  patent  would  have  been  more  apparent  had  the 
claim  been  for  a  method  of  conveying  chlorine  from  place 
to  place,  but  even  that  claim  to  be  of  any  value  should 
have  included  some  description  of  apparatus. 

(2.)  The  observations  of  extensive  practice  prove  that 
in  every  properly  conducted  chlorination  operation  there 
is  no  premature  precipitation  of  gold,  the  presence  of 
an  excess  of  chlorine  preventing  this  ;  but,  even  were 
such  the  case,  instead  of  cyanides,  it  surely  would 
be  cheaper,  more  convenient,  and  efficacious,  to  add 
more  chlorine,  were  the  quantity  insufficient  to  sustain 
the  metals  in  solution.  On  a  goldfield  the  use  of  cyanides 
would  be  objectionable  and  would  materially  increase 
cost ;  the  suggestion  bears  the  stamp,  unfortunately  too 
often  met  with,  of  laboratory  chemistry. 

NEWBERY  AND  YAUTIN,   1887. 
Specification  No.  4609,  2 8th 'March,  1887,  is  for  : 

Improvements  in  wet  or  hydro-metallurgical  method  of  extracting 
gold  from  crushed  or  other  finely  divided  auriferous  material. 

We,  James  Cosmo  Newbery,  of  the  Technological  Museum,  Mel- 
bourne, in  the  Colony  of  Victoria,  Bachelor  of  Science,  and  Claude 
Theodore  James  Yautin,  of  Jackson-street,  St.  Kilda,  in  the  said 
colony,  metallurgical  engineer,  do  hereby  declare  the  nature  of  this 
invention,  and  in  what  manner  the  same  is  to  be  performed,  to  be 
particularly  described  and  ascertained  in  and  by  the  following  state 
ment : 

Our  invention  consists  of  certain  improvements  in  what  is  known  as 

L 


146  Remedies. 

the  wet  or  hydro-metallurgical  method  of  extracting  gold  from  crushed 
or  other  finely  divided  auriferous  material. 

This  "  wet "  or  hydro-metallurgical  method  may  be  said  to  consist, 
firstly,  in  submitting  the  auriferous  material  under  treatment  to  the 
action  of  such  reagents  (either  in  form  of  a  solution  or  gas)  as  circum- 
stances may  direct,  that  will  so  react  on  the  gold  sought  for,  as  to  form 
soluble  salts  of  it,  in  which  condition  it  may  be  leached  or  dissolved 
out  from  material  under  treatment.  As  to  the  first  or  dissolving  part, 
it  has  been  ascertained  that  the  reagents  used  to  convert  the  gold 
sought  for  into  a  soluble  form  operate  more  quickly  when  they  are 
applied  under  pressure.  Thus,  as  an  example,  chlorine  either  when 
applied  in  form  of  gas  or  in  solution,  under  a  pressure  greater  than 
that  of  the  atmosphere,  combines  with  and  converts  the  gold  into  a 
chloride  more  rapidly  than  when  applied  under  normal  atmospheric 
pressure.  Now,  hitherto  when  chlorine  has  been  used  under  pressure 
greater  than  that  of  the  atmosphere,  such  pressure  has  been  obtained 
by  providing  great  excess  of  chlorine  gas  (De  Lacy  and  Hears)  beyond 
that  necessary  to  combine  with  the  gold,  and  this  excess  is  utterly 
valueless  in  the  process,  except  as  a  means  of  producing  pressure.  Now 
we  substitute  air  under  pressure  instead  of  the  excess  of  chlorine  as  a 
means  of  producing  necessary  pressure,  and  this  pressure  we  obtain  by 
means  of  any  known  air  compressing  device  such  as  an  air  pump. 

When  chlorine  is  used  great  advantage  is  gained  by  employing  an 
air  pressure  of  about  four  atmospheres,  for  thereby  any  chlorine  that 
may  exist  in  form  of  gas  in  the  vessel  containing  the  material  under 
treatment  will  be  liquefied  (1)  and  dissolved  in  the  water  added,  in 
which  condition  we  find  its  action  greatly  accelerated. 

Secondly,  one  of  the  greatest  objections  to  the  hydro-metallurgical 
method  hitherto  has  been  the  length  of  time  required  for  the  draining 
off,  filtering,  or  removal  of  the  solutions  from  the  material  under  treat- 
ment. Now  we  greatly  reduce  the  time  by  the  application  of  an 
aspirator,  and  preferably  by  a  vacuum  pump  as  such  aspirator,  to  the 
lower  portion  of  the  filter  containing  such  material,  in  order  to  draw  or 
suck  the  solution  through  the  filter-bed,  and  out  of  the  filter.  We 
prefer  a  vacuum  pump  as  an  aspirator  because  we  find  that  a  jigging 
motion  is  thereby  given  to  the  material  while  the  solution  is  being 
withdrawn  or  sucked  out,  which  motion  prevents  the. material  from 
setting  too  tightly  on  the  filtering  medium  (2);  having  obtained  the 
auriferous  solution  from  the  auriferous  material  in  a  manner  herein  set 
forth  we  proceed  to  extract  the  gold  therefrom  in  the  following  manner, 
although  we  do  not  claim  this  method  of  extraction  as  part  of  our 
invention  :  We  provide  thick  or  deep  beds  of  rough  charcoal  (3),  that 


Remedies.  147 

is,  charcoal  in  pieces  and  not  in  dust,  and  by  preference  we  arrange 
such  charcoal  beds  in  the  form  of  narrow  columns  contained  in  earthen- 
ware pipes.  Through  these  columns  we  pass  the  auriferous  solution, 
which  is  thereby  rapidly  decomposed,  and  deposits  its  gold  on  the 
charcoal,  from  which  we  obtain  it  by  burning,  as  is  well  understood. 

Having  now  particularly  described  and  ascertained  the  nature  of  the 
said  invention,  and  in  what  manner  the  same  is  to  be  performed,  we 
declare  that  what  we  claim  is : 

1.  The  application  of  air  pressure  in  the  wet  or  hydro-metallurgical 
method  of  extracting  gold  from  crushed  or  other  finely  divided  auri- 
ferous material  for  the  purpose  of  accelerating  the  action  of  the  chlorine 
and  other  reagents  used  substantially  as  herein  described  and  explained. 

2.  The  application  of  an  aspirator  for  the  purpose  of  sucking  the 
auriferous  solution  through  the  filtering  medium  and  out  of  the  filter, 
such  aspirator  being  preferably  in  the  form  of  a  vacuum  pump,  so  as  to 
give  a  jigging  motion  to  the  material  under  treatment,  substantially 
as  herein  described  and  explained. 

(1.)  These  patentees  by  using  this  system  of  air  pres- 
sure confine  all  the  chlorine  gas  within  the  liquid  of  the 
charge,  thus  enabling  the  gold  dissolving  operation  to  be 
carried  out  by  means  of  a  concentrated  solution  obtained 
from  a  minimum  quantity  of  chemicals. 

(2.)  This  is  the  first  and  only  invention  in  this  long 
series  of  patents  of  any  method  to  improve  or  hasten 
filtration,  and  it  is  one  of  the  most  important  points  in 
connection  with  the  process  of  chlorination ;  the  advan- 
tage and  importance  of  this  point  will  be  further  discussed 
when  the  list  of  patent  specifications  are  disposed  of. 

(3.)  In  the  United  States  on  llth  February,  1880, 
patent  No.  227,963  was  applied  for  by  Wm.  Morris 
Davis,  of  Philadelphia,  and  granted  on  25th  May,  1880,. 
for  the  decomposition  of  gold  chloride  (Au  C13)  by  carbon 
— "  animal,  vegetable,  or  mineral  " — notwithstanding 
that  this  should  have  been  a  matter  of  general  know- 
ledge, for,  at  the  annual  meeting  of  the  Institution  of 
Mining  Engineers,  held  at  .New  York,  Professor 


148  Remedies. 

Egleston,  of  the  School  of  Mines  of  that  city,  stated  on 
the  19th  February — three  months  before  the  granting  of 
the  patent — 

A  charcoal  filter  is  now  used  to  precipitate  gold  from  its  solutions 
on  a  large  scale.  Mr.  Newbery,  the  Australian  geologist,  published, 
some  years  ago,  a  paper  relating  to  this  subject.  * 

Me  ARTHUR  AND  OTHERS,   1887. 

Specification  No.  14,174,  19th  October,  1887,  accepted 
10th  August,  1888,  of  John  Stewart  McArthur,  Kobert 
Wardrop  Forrest,  and  William  Forrest ;  the  claims  of 
which  are  as  follows  : 

1.  The  process   of  obtaining  gold  and   silver  from   ores  and  other 
compounds,  consisting  in  dissolving  them  out  by  treating  the  powdered 
ore  or  compound  with  a  solution  containing  cyanogen  or  a  cyanide  or 
cyanogen-yielding  substance,  substantially  as  hereinbefore  described. 

2.  The  process  of  obtaining  gold  and  silver  from  ores  and  other  com- 
pounds, consisting  in  dissolving  them  out  by  treating  the  powdered  ore 
or  compound  with  a  dilute  solution  containing  a  quantity  of  cyanogen 
or  a  cyanide  or  cyanogen-yielding  substance,  the  cyanogen  of  which  is 
proportioned  to  the  gold  or  silver  or  gold  and  silver,  substantially  as 
hereinbefore  described. 

Cyanide  is  one  of  the  chemicals  frequently  used  in  the 
arts  for  keeping  gold  in  solution ;  but  its  practical 
applicability  to  metallurgical  operations  on  a  large  scale 
is  questionable  from  almost  every  point  of  view.  Some 
arrangements,  which  would  be  more  or  less  complicated 
and  ineffectual,  would  have  to  be  made  to  recover  the 
cyanide  after  use,  for  considerations  entirely  outside 
economy. 

The  reason  why  a  patent  is  granted  for  the  use  of  this 

chemical  as  a  dissolvent  for  gold  "is  one  of  those  things 

no  fellow  can  understand."     In  most  standard  chemistry 

cyanide  is  mentioned  for  such  a  purpose  ;  its  properties 

*  Trans.  Am.  Inst.  Min.  Eng.,  vol.  viii.,  p.  454. 


Remedies.  149 

are  well  known ;  it  is  in  daily  use  as  a  gold  solvent  in 
certain  arts ;  no  attempt  is  made  to  describe  or  even  hint 
at  any  practical  method  whereby  it  might  be  applied, 
general  statements  as  to  its  properties  being  alone  the 
subject  matter  of  the  specification.  It  would  almost 
seem  as  reasonable  to  grant  a  patent  for  dissolving  sugar 
by  tea  on  a  larger  scale  than  in  the  ordinary  tea  cup, 
without  even  referring  to  the  nature  of  the  apparatus 
in  which  the  operation  should  be  carried  out. 

VAUTIN,  1887. 

Specification  No.  15,574,  applied  for  14th  November, 
1887,  accepted  December  20th,  1887,  Claude  Theodore 
James  Yautin,  is  for  : 

Improvements  in  the  apparatus  forming  the  plant  employed  for  the 
extraction  of  gold  by  what  is  known  as  the  "  wet  "  or  hydro-metallur- 
gical process  from  crushed  or  other  finely  divided  auriferous  material. 

The  complete  process  employed  consists  of  treating  the  pulverised 
auriferous  material  with  chlorine  or  other  equivalent  re-agent  in  the 
form  of  gas  or  in  solution  applied  under  a  pressure  greater  than  that  of 
the  atmosphere  according  to  a  part  process  patented  to  J.  C.  Newbery, 
in  conjunction  with  myself,  under  No.  4609,  dated  March  28th, 
1887. 

This  I  carry  out  by  means  of  an  air  force  pump  and  a  closed  chamber, 
which  closed  chamber  is  caused  to  agitate  the  contents  under  treatment 
by  rotation  from  some  suitable  source  of  motion.  The  chamber  is  pro- 
vided with  a  suitable  hermetically  closing  door,  and  is  connected  to  the 
said  air  force  pump,  and  is,  as  aforesaid,  capable  of  rotation,  so  that 
after  the  auriferous  material  has  been  subjected  for  a  sufficient  time  to 
the  action  of  the  chlorine  or  other  re-agent,  the  said  chamber  may  be 
inverted,  and  the  charge  delivered  into  a  filtering  vessel  conveniently 
placed  beneath  it. 

The  auriferous  solution  mixed  with  the  pulverised  material,  is  now 
passed  into  this  filtering  or  leaching  vessel,  and  the  solution  is  drawn 
through  the  filtering  medium  by  means  of  suction  produced  by  a  suction 
pump,  which  is  so  constructed  as  to  produce,  in  every  stroke,  a  partial 
reflux  through  the  filtering  medium,  of  the  withdrawn  liquid  charge,  so 
as  to  keep  the  filtering  medium  cleansed  and  free  from  choking,  as 


150 


Remedies. 


particularly  described  in  my  application  for  a  patent  under  even  date 
herewith. 

From  the  said  suction  pump,  the  auriferous  solution  is  discharged 
into  a  suitable  vat,  through  which  also  air  or  steam  is  passed.     From 


this  point  the  auriferous  solution  is  passed  through  a  filter  of  charcoal 
or  other  suitable  re-agent,  consisting  of  successive  beds  of  alternately 
rough  and  fine  pieces  of  charcoal  or  other  re-agent,  arranged  in  vertical 
beds  or  columns  of  considerable  height.  The  auriferous  solution  is  here 


Remedies. 


151 


rapidly  decomposed,  and  deposits  its  gold  upon  the  charcoal  or  other 
re-agent,  from  which  it  is  obtained  in  any  convenient  manner. 

In  order  that  my  invention  may  be  the  better  understood,  I  now 
proceed  to  describe  the  nature  of  the  apparatus  in  connection  with  the 

Fig.M. 


Fig.  21 


drawings  hereunto  annexed,   reference   being  had   to  the  letters  and 
figures  marked  thereon. 

Fig.   19  is  a  general  elevation  of  my  apparatus,  forming  the  plant 
employed  for  the  extraction  of  gold. 


152  Remedies. 

Fig.  20  is  a  sectional  detail  of  the  closed  chamber jn  which  the  gold  is 
acted  on  by  any  suitable  re-agent  such  as  chlorine. 

Eig.  2.1  is  a  sectional  detail  through  the  filtering  vessel  or  leaching 
vessel  when  the  flow  is  downwards. 

Fig.  22  is  a  modified  detail  of  my  filtering  vessel  with  cover  when  the 
flow  is  reversed  or  taken  upwards. 

a  are  the  hoppers  from  which  the  pulverised  ore  is  discharged  for 
treatment  into  the  closed  vessels  b  by  chlorine,  bromine,  or  other 
equivalent  re-agent,  in  a  liquid  or  gaseous  condition,  which  is  applied 
under  pressure,  and  which  is  caused  to  re-act  on  the  ore  under  a  pressure 
greater  than  that  of  the  atmosphere  by  means  of  an  air  force  pump  c. 
This  vessel  b,  shown  in  detail  in  Fig.  20,  is  strongly  constructed  of  iron 
or  similarly  suitable  material,  to  carry  considerable  internal  pressure. 
It  is  hermetically  closed  by  a  man-hole  door  d,  by  which  the  charge  of 
ore  is  admitted  when  required,  and  discharged  when  sufficiently  treated  ; 
I  have  found  it  important  to-  effect  the  lining  of  this  chamber  in  the 
following  manner  :  Within  the  iron  shell  I  apply  a  coating  of  lead  to 
protect  the  former  against  the  action  of  the  chemical  re  agents  or  salts, 
and  within  that  I  apply  another  protective  coating  of  wood,  earthen- 
ware, or  suitable  material,  to  prevent  the  abrasion  of  the  lead  lining  by 
the  agitation  of  the  ore  therein  by  rotation.  The  gas  or  air  communica- 
tions I  effect  through  a  suitable  stop  valve  e,  to  which  the  pipes  are 
connected  by  a  suitable  union.  By  this  means,  after  the  admixture  of 
the  pulverised  ore  and  the  chlorine  or  other  chemical  re-agent  has  been 
made  in  this  chamber,  compressed  air  is  admitted  from  the  air  compressor 
c,  until  the  required  working  pressure  of  about  five  atmospheres  per 
square  inch  is  arrived  at.  The  valve  e  is  then  screwed  down,  and  the 
pipes  detached,  whilst  agitation  of  the  contents  by  the  rotation  of  the 
vessel  proceeds.  Before  discharge  of  the  contents  into  the  filtering 
vessel  or  leaching  tub  f,  the  compressed  air  and  gas  is  allowed  to 
pass  through  this  valve  e  by  a  suitable  connection  into  a  solution  of 
lime  water  in  the  tub  g,  to  absorb  noxious  vapours.  The  ore  so  treated 
is  then  discharged,  by  inversion  of  the  chamber  &,  into  the  leaching  tubs 
or  filters/  (shown  in  alternative  detail  in  Figs.  21  and  22).  The  leach- 
ing or  separating  of  the  auriferous  suction  from  the  pulverised  material 
mixed  therewith,  is  effected  by  the  direct  suction  of  a  pump  p  through 
the  alternative  suction  pipe  h  (Fig.  21),  a  flow  of  water  being  main- 
tained as  long  as  required.  In  the  apparatus,  as  shown  in  Fig.  21,  this 
operation  is  carried  out  by  filtration  downwards.  In  Fig.  22  the  inverse 
process  is  used,  the  solution  being  withdrawn  upwards  through  the 
filtering  medium  k,  consisting  of  a  perforated  wooden  diaphragm 
covered  with  a  suitable  filtering  medium  such  as  canvas  or  asbestos,  a. 
flow  of  water  being  maintained  through  the  supply  pipe,/. 


Remedies.  153 

In  this  case  the  filtering  vessel  or  leaching  tub  is  conveniently  closed 
by  a  cover  I  bolted  down  upon  the  open  mouth  of  the  vessel.  The 
pulverised  material  and  the  filtering  medium  are  prevented  from 
choking  by  a  reflux  action  from  the  suction  pump;?  through  the  suction 
pipe  h  or  AT,  particularly  as  described  in  the  application  for  a  patent 
made  by  me  under  even  date  herewith. 

After  sufficient  leaching  of  the  ore  or  pulverised  material  has  been 
effected  in  this  leaching  vessel,  the  solid  material  is  conveniently  dis- 
charged by  reversal  of  the  filtering  vessel,  and  taken  away  by  a  trolley 
or  other  convenient  means.  To  prevent  the  filter  bed  TO,  as  shown  in 
Fig.  21,  from  being  discharged  by  reversal  of  the  filter,  I  provide  a  series 
of  obliquely  inclined  wooden  slats  interspersed  between  the  filtering 
medium,  to  keep  it  in  place  even  during  reversal  of  the  said  filter  vessel. 
The  auriferous  solution  so  withdrawn  from  the  filtering  vessels  is 
delivered  into  the  vat  q,  where  it  is  treated  with  a  jet  of  steam  or  air, 
to  drive  off  any  free  chlorine  or  uncombined  re-agent  that  may  remain 
in  the  solution.  The  solution  is  then  passed  through  a  filter  r,  com- 
posed of  charcoal  or  other  re-agents,  which  is  formed  of  alternate  layers 
of  coarse  and  fine  pieces  respectively,  and  is  of  considerable  height  and 
small  sectional  area.  The  gold  is  here  precipitated  from  its  solution 
and  is  recovered  from  the  material  of  the  said  filter  by  burning  or  other 
suitable  chemical  process. 

The  moving  portions  of  my  apparatus  are  conveniently  driven  by  a 
steam  engine  s  or  other  convenient  motor. 

Having  now  particularly  described  and  ascertained  the  nature  of  my 
said  invention,  and  in  what  manner  the  same  is  to  be  performed,  I 
declare  that  Avhat  I  claim  is  : 

1.  In  a  hydro-metallurgical  gold  extracting  apparatus  such  as  herein 
described,  the  combination  together  of  an  air  forcing  pump  or  compressor,, 
a  hermetically  closed  vessel  in  which  the  gold  is  acted  on  by  any  suitable 
re-agent,   a  filtering  vessel,   a  reflux  suction  pump,   an  air   or  steam 
agitated  vat,  and  a  deep  filter  bed  of  charcoal  or  other  suitable  re-agent, 
substantially  as  and  for  the  purposes  set  forth. 

2.  In  a  hydro-metallurgical  gold  extracting  apparatus  such  as  herein 
described,  the  combination  of  an  air  forcing  pump  or  compressor  and  a 
hermetically  closed  vessel  in   which   the   gold  is  acted  upon  by  any 
suitable  re-agent,  with  a  filtering  vessel,  substantially  as  described. 

3.  In  a   hydro-metallurgical   gold    extracting  apparatus  such  as    is 
herein  described,  the  combination  of  a  vessel  in  which  the  gold  is  acted 
on  by  any  suitable  re-agent,  with  a  filtering  vessel  and  a  suction  pump, 
drawing  the  solution  therefrom,  and  giving  a  part  reflux  action  of  the 
charge  to  keep  the  said  filtering  medium  from  becoming  choked,  sub- 
stantially as  described. 


154  Remedies. 

4.  In   a   hydro-metallurgical   gold   extracting  apparatus  such  as    is 
herein  described,  the  combination  of  a  vessel  in  which  the  gold  is  acted 
on  by  any  suitable  re-agent,  and  a  filtering  vessel  and  suction  pump 
drawing  the  solution  therefrom  with  a  part  reflux  action  of  the  charge 
with  an  air  or  steam  agitated  vessel,  and  a  deep  filter  of  charcoal  or 
other  suitable  re-agent,  substantially  as  described. 

5.  In   a   hydro -metallurgical   gold   extracting   apparatus  such  as  is 
herein  described,  the  construction  of  the  vessel  in  which  the  gold  is 
acted  on  by  any  suitable  re-agent,  substantially  as  described. 

6.  In   a   hydro-metallurgical   gold   extracting    apparatus  such  as  is 
herein  described,  the  construction  of  the  leaching  or  filter  vessel,  sub- 
stantially as  described. 

The  foregoing  is  a  specification  for  a  suitable  combina- 
tion of  devices  to  work  the  improvements  secured  by 
patent  No.  4609,  1887.  The  main  points  of  difference 
between  this  barrel  and  those  hitherto  used  for  the  same 
purpose,  is  that  the  trunnions  are  solid,  anything  to  be 
forced  into  it  after  charging,  goes  through  a  valve  with 
screw  tap  fixed  on  the  circumference,  also  that  the  lead 
lining  is  protected  from  abrasion,  &c.,  by  a  lining  of 
wood  or  other  suitable  substance.  The  other  essential 
points  in  the  plant  are  the  leaching  vats  worked  by  a 
vacuum  jigger  of  suitable  construction. 

POLLOK,  1887. 

Specification  No.  17,495,  20th  December,  1887,  ac- 
cepted 24th  August,  1888,  of  James  Holms  Pollok,  ot 
the  University  of  Glasgow,  assistant  to  the  professor  of 
chemistry  in  that  university.  The  following  excerpts 
from  the  specification  will  be  sufficient  to  explain  the 
nature  of  the  claims  : 

My  invention  relates  to  improvements  in  the  wet  method  or  process 
for  the  extraction  of  gold  by  chlorine  from  crushed  ores,  such  as  quartz, 
or  from  other  finely  divided  auriferous  material,  and  more  particularly 
from  refractory  ores  or  tailings. 

My  invention  greatly  facilitates  the  production  of  a  high  pressure  (1), 
and  thus  shortens  the  time  taken  for  extracting  gold  from  ore  or  other 


Remedies.  155 

auriferous  material  by  chlorination  under  pressure,  and  makes  the 
extraction  thereof  more  economical  and  complete  than  has  hitherto  been 
effected. 

It  has  long  been  known  that  pressure  in  the  vessels  wherein  the 
extraction  of  gold  from  auriferous  material  takes  place  greatly  assists 
that  extraction,  and  several  processes  have  been  devised  for  the  extrac- 
tion of  gold  by  chlorination  under  pressure.  Amongst  these  processes 
are  those  known  as  the  De  Lacy  process,  Mear's  process,  and  the 
ISTewbery-Vautin  process.  In  the  De  Lacy  process,  pressure  is  deve- 
loped by  generating  a  considerable  excess  of  chlorine  in  the  vessel  in 
which  the  extraction  is  conducted  (2).  In  Mear's  process  pressure  is 
obtained  by  pumping  chlorine  gas  into  the  cylinder  (3),  whilst  in  the 
Newbury-Vautin  process  pressure  is  obtained  by  pumping  atmospheric 
air  into  the  vessels.  Each  of  these  processes  has  been  more  or  less 
successful,  and  the  success  has  varied  according  to  the  pressure  pro- 
duced (4)  and  the  cost  of  producing  it. 

According  to  my  invention  I  extract  gold  from  the  ores  or  other 
auriferous  material  by  chlorination  under  pressure  produced  by 
hydraulic  means.  In  using  hydraulic  pressure,  I  am  enabled  to 
produce  any  desired  degree  thereof  in  a  short  time  and  at  a  small 
cost  (5). 

While  the  production  of  pressure  in  the  vessels  by  hydraulic  means 
is  the  essential  feature  of  my  improvements  on  the  wet  chlorination 
process,  I  give  the  following  description  of  working  the  process  so  that 
my  improvements  may  be  more  readily  understood  and  its  advantages 
•distinctly  seen.  The  entire  process  may  be  considered  as  divided  into 
four  stages  as  follows  : 

First.  The  crushed  ore  is  roasted  to  expel  the  sulphur.  The  pyrites 
or  other  metallic  sulphides  which  envelop  the  gold  and  thus  make  the 
ore  refractory  are  by  roasting  rendered  porous  or  spongy  by  the  removal 
of  the  sulphur,  which  if  allowed  to  remain  would  have  taken  up  a  large 
quantity  of  the  chlorine  in  the  vessel  and  therefore  rendered  that 
chlorine  useless  for  the  purpose  of  extracting  the  gold  (6).  Where 
no  sulphur  or  only  a  small  quantity  exists,  it  is  unnecessary  to  roast 
the  ore  (7). 

Secondly.  The  ore  is  then  placed  in  a  cylinder  A,  shown 
in  longitudinal  section  in  Fig.  23.  This  cylinder  has  a  lead 
lining  a1  within  the  cast-iron  exterior,  and  a  lining  of  wood 
bl  (8)  within  that  again,  as  shown  in  longitudinal  section  at 
Fig.  23.  Bleaching  powder  as  the  source  of  chlorine  and  sulphuric 
acid  or  other  re-agent  for  liberating  the  chlorine  from  the  bleaching 
powder  are  also  charged  into  the  cylinder  (9).  The  cylinder  is  provided 
with  a  charging  hole  B,  and  a  covering  door  0,  as  shown  in  Fig.  23, 


156 


Remedies. 


through  which  the  charge  is  placed  in  the  cylinder,  the  door  C 
being  removed  for  charging  it  by  unscrewing  the  nuts  which  retain  it 
on  the  studs  as  shown  at  Fig.  23.  After  the  ore,  bleaching 
powder,  and  sulphuric  acid,  or  other  re-agent  used,  are  charged  into  the 
cylinder  (10),  the  cylinder  is  closed  by  replacing  the  door  C,  and 
tightening  the  nuts  by  which  it  is  pressed  against  and  held  over  the^ 
charging  hole  B.  So  soon  as  this  is  done  water  under  pressure  is 
admitted  into  the  cylinder  through  the  cock  D,  a  pipe  being  coupled  to- 
the  screwed  end  of  the  cock  connected  to  a  pump,  accumulator,  or  other 
source  of  supply.  The  admission  of  water  under  pressure  is  continued 
until  the  pressure  within  the  cylinder  reaches  to  at  least  100  Ib.  per 
square  inch  (11),  when  the  cock  D  is  closed,  and  the  pipe  connected  to- 


Fig.  23 


the  said  cock  is  disconnected.  The  cylinder  A,  as  shown  at  Fig.  23r 
is  carried  upon  rollers,  and  is  rotated  by  means  of  a  spur  pinion 
gearing  into  a  circle  of  spur  teeth  around  the  cylinder  (not  shown  in 
the  drawings),  such  an  arrangement  being  well  understood  and  used 
in  connection  with  various  rotating  vessels  in  chemical  works.  The 
rotation  of  the  vessel  A  is  continued  for  from  half  an  hour  to  one  hour, 
when  the  whole  of  the  gold  will  be  found  to  have  been  dissolved;  the 
pressure  having  forced  the  chlorinating  liquid  into  the  pores  of  the 
ore  (12). 

The  proportions  of  water  and  ore  are  regulated  by  the  amount  of  ore 
placed  in  the  cylinder.  I  find  it  convenient  to  use  cylinders  A  of  about 
42  cubic  feet  capacity,  and  to  introduce  about  1  ton  of  ore  at  each 


Remedies.  157 

charge.  With  a  vessel  of  this  capacity  and  with  the  aforesaid  charge 
of  ore,  about  25  cubic  feet  of  water  will  have  been  forced  into  the 
vessel  (13)  when  the  pressure  reaches  100  Ib.  per  square  inch,  and  I 
find  as  a  general  rule  that  this  is  a  good  proportion  to  adopt  for  success- 
ful chlorination.  When  it  is  desirable  from  the  light  and  spongy 
character  of  the  ore  or  otherwise  to  use  less  water,  this  is  easily  effected 
by  introducing  more  ore  into  the  cylinder. 

Thirdly.  When  the  chlorination  of  the  charge  is  completed  the  rota- 
tion of  the  vessel  A  is  stopped,  care  being  taken  that  the  vessel  A  is 
stopped  in  such  position  that  the  cock  D  is  at  its  highest  point.  The 
cock  D  has  then  a  pipe  connected  to  it  leading  to  chambers  containing 
slaked  lime.  The  cock  D  is  then  opened  and  the  excess  of  chlorine 
flowing  out  therethrough  into  the  chambers  containing  the  slaked  lime 
is  reconverted  into  bleaching  powder,  the  last  portions  of  chlorine  being 
drawn  out  of  the  chamber  A  by  the  action  of  an  exhaust  pump  con 
nected  to  the  slaked  lime  chambers  (14)  .... 

What  follows  here  is  a  description  of  how  the  plant  is 
arranged  for  the  successful  working  of  this  "  invention." 
The  claims  for  a  patent  are  as  follows  : 

The  production  of  pressure  to  a  vessel  wherein  the  wet  process  or 
method  of  extracting  gold  by  chlorination  is  conducted  by  forcing  water 
into  the  said  vessel  by  means  of  a  hydraulic  pump,  accumulator,  or 
other  water  forcing  apparatus,  substantially  as  hereinbefore  de- 
scribed (15). 

(1.)  It  would  be  interesting  to  learn  how  the  patentee's 
"  invention  "  facilitates  the  production  of  pressure. 

(2.)  This  statement  is  incorrect,  and  betrays  an  ignorance 
of  the  nature  of  Mr.  De  Lacy's  invention. 

(3.)  This  statement  is  also  incorrect,  and  bears  the  same 
construction  as  the  one  preceding. 

(4.)  This  statement  is  quite  incorrect  and  entirely  mis- 
leading. 

(5.)  This  is  equally  applicable  to  other  methods  of 
obtaining  pressure. 

(6.)  This  has  been  recognised  and  pointed  out  by  chlori- 
nators  for  the  past  forty  years. 


158  Remedies. 

(7.)  This  statement  is  misleading,  because  it  is  not 
always  a  fact. 

(8.)  The  Yautin  barrel  covered  by  Patent  No.  15,574, 
1887. 

(9.)  In  common  and  daily  use,  and  known  by  chlori- 
nators  for  the  past  forty  years. 

(10.)  It  would  be  interesting  to  see  the  device  or  learn 
the  manner  proposed  to  charge  this  barrel  with  economy 
and  despatch. 

(11.)  With  a  barrel  so  constructed  it  would  be  impos- 
sible to  fill  it  in  the  manner  described  without  leaving  a 
large  quantity  of  air  inside ;  then,  though  a  hydraulic  press 
be  found  necessary  to  attain  pressure,  if  a  tap  were  turrfed 
which  let  the  air  out,  no  pressure  would  remain  in  the 
barrel ;  in  any  case  a  pressure  of  100  Ib.  per  square  inch 
is  an  excess  of  about  40  Ib.  more  than  advantageous. 

(12.)  All  other  pressure  produces  like  results. 

(13.)  These  dimensions  and  quantities  must  of  necessity 
leave  a  large  proportion  of  air  in  the  barrel,  which  would 
compose  the  cushion  sustaining  the  pressure. 

(14.)  It  would  be  an  interesting  experiment  for  the 
patentee  to  determine  the  relative  proportions  of 
chloride  of  lime,  chloride  and  chlorate  of  calcium,  which 
would  result  from  the  adoption  of  the  method  proposed, 
and  whether  the  cost  of  applying  it  would  not  exceed  in 
value  the  proportion  of  the  re-agent  recovered. 

(15.)  Though  air  would  be  the  active  element  in  pro- 
ducing pressure  when  working  this  "invention,"  no  men- 
tion is  made  of  it  in  the  claim,  the  statement  of  what 
would  be  the  real  state  of  affairs  was  incautiously  inserted 
into  the  provisional  specification,  viz.  : 

So  soon  as  the  vessel  is  thus  closed  water  under  the  pressure  of 
a  sufficient  head  is  admitted  until  the  air  in  the  vessel  is  compressed  to 


Remedies.  1591 

such  to  an  extent  as  will  cause  the  whole  or  nearly  the  whole  of  the- 
chlorine  to  remain  in  solution. 

This  is  the  Newbery-Vautin  patent  with  the  disad- 
vantage added  of  making  the  chemical  solution  inside  the 
barrel  unnecessarily  dilute  and  consequently  less  effective. 

There  are  three  sheets  of  drawings  attached  to  the 
specification,  none  of  which  have  any  reference  to  the 
claim.  The  filter  proposed  is  about  as  original  as  the 
suggestions  contained  in  the  paragraphs  referred  to  by 
figures  (6)  and  (9). 

CROOKES,  1888. 

Specification  No.  7867,  applied  for  29th  May,  1888, 
accepted  29th  June,  1888,  of  William  Crookes,  is  set 
forth  as  follows  : 

In  experimenting  on  various  samples  of  auriferous  ores,  I  have  found 
it  possible  to  treat  some  efficiently  by  commercial  perchloride  of  iron, 
but  other  ores  require  a  somewhat  different  treatment  to  prevent  a 
large  percentage  of  the  gold  being  lost  in  the  tailings. 

Now,  the  main  object  of  the  present  invention  is  to  secure  the 
largest  available  yield  of  gold,  and  this  I  do  by  subjecting  crushed 
auriferous  ores  to  the  action  of  a  solution  of  perchloride  of  iron,  with 
or  without  common  salt,  in  the  presence  of  heat,  either  with  the  addi- 
tion of  nitrate  of  soda,  nitrate  of  potash,  or  equivalent  nitrate,  or 
peroxide  of  manganese,  or  free  mineral  acid  (1). 

When  the  ores  contain  only  a  small  quantity  of  sulphurets  or  other 
minerals  attackable  by  perchloride  of  iron,  I  prefer  to  use  a  fairly 
strong  solution  of  perchloride  of  iron,  of  about  sp.  gr.  1.150  [30  Twad.] 
(which  solution  should  not  be  neutral),  and  to  this  I  add  as  much 
common  salt,  in  crystals,  as  the  solution  of  perchloride  of  iron  will 
dissolve  in  #ie  cold.  To  this  mixture,  contained  in  a  suitable  tank  (2), 
I  add  the  crushed  ore  which  is  to  be  operated  upon.  It  should  be 
remarked  that  common  salt  need  only  be  used  when  silver  is  present  in 
the  ore  in  an  appreciable  percentage.  To  the  mixture  I  add  nitrate  of 
soda  or  its  equivalent,  or  well-washed  precipitated  peroxide  of  man- 
ganese (Weldon  mud),  in  the  proportion  of  one  part  of  the  peroxide  of 
manganese  to  three  parts  of  the  perchloride  of  iron  present ;  or  in  the 
case  of  the  nitrates,  one  part  of  such  oxidising  element  to  five  parts  of 


160  Remedies. 

the  perchloride  of  iron,  and  I  heat  the  whole  to  a  temperature  of 
95  deg.  to  100  deg.  C.,  with  continuous  stirring  by  any  suitable 
means  (3). 

The  result  of  this  mode  of  treatment  will  be  appreciated  from  the 
fact  that  the  gold  is  not  infrequently  locked  up  in  mineral  matter  that 
resists  the  action  of  the  perchloride  of  iron  (4).  In  such  a  case,  the 
addition  of  peroxide  of  manganese,  or  nitrate  of  soda,  puts  the  per- 
chloride of  iron  into  a  kind  of  unstable  equilibrium  (5),  leaving  the 
extra  atom  of  chlorine  available  for  the  conversion  of  the  gold  to  a 
chloride 

Here  follows  a  statement  of  the  reactions  which  take 
place  when  certain  chemicals  are  mixed  together  in  a 
manner  as  described.  The  claims  for  the  patent  are  as 
follows  : 

1.  In  the  treatment  of  auriferous  ores  for  the  extraction  of  gold 
therefrom,  the  use  of  peroxide  of  manganese  in  combination  with  per- 
chloride of  iron  as  above  set  forth  (6). 

2.  The  use,  as  an  oxidising  agent,  in  the  treatment  of  auriferous 
ores  by  perchloride  of  iron,  of  nitrate  of  soda,  nitrate  of  potash,  or  an 
equivalent  nitrate,  alone  or  in  combination  with  peroxide  of  manganese. 

3.  The  revivification  of  spent  chloride  of  iron  in  the  manner  and  for 
the  purpose  above  set  forth. 

(1.)  The  main  point  in  the  specification,  is  the  use  of 
perchloride  of  iron  as  an  agent  for  dissolving  gold,  but  as 
every  one  knows  who  has  any  knowledge  of  chemistry 
that  it  is  the  extra  equivalents  of  chlorine  available  in  the 
perchloride  of  iron  which  is  the  active  agent,  therefore  it 
is  not  very  apparent  where  the  advantage  is  to  be  gained 
by  substituting  perchloride  of  iron  for  chloride  of  lime, 
especially  when  the  latter  may  be  bought,  not  as  a 
product  from  which  chlorine  may  be  extracted,  but 
according  to  the  guaranteed  quantity  of  available 
chlorine  it  contains. 

(2)  and  (3.)  A  tolerably  large  order  for  tanks  and 
boiling  plant,  fuel,  and  stirring  apparatus  if  any  such 
method  were  applied  to  the  ore  from  a  mine  with 


Remedies.  161 

even  the  most  moderate  output ;  in  addition  to  which 
the  vessels  would  have  to  be  of  a  material  which  would 
resist  the  action  of  chlorine. 

(4.)  In  such  a  case  how  would  the  perchloride  of  iron 
get  inside  the  pyrites  grain  to  dissolve  the  gold  ?  Surely 
it  is  not  intended  to  decompose  the  pyrites  by  this 
solvent  agency  ?  if  so,  it  would  seem  to  be  a  far  more 
costly  method  than  to  decompose  by  calcination. 

(5.)  "  A  kind  of  unstable  equilibrium"  is  not  sufficient, 
complete  breaking  down  would  be  necessary  before  the 
chlorine  equivalent  was  available. 

(6.)  Unless  in  this  operation  oxidizing  agents  were 
kept  in  considerable  excess  and  no  bodies  were  present 
to  prevent  their  action  on  perchloride  of  iron,  the  dis- 
solving process  would  come  to  a  standstill.  Mr.  Charles 
Howard  Aaron,  a  worker  in  the  United  States,  with 
years  of  practical  experience,  says  :* 

Iron  perchloride  does  not  dissolve  gold  in  the  presence  of  iron 
protosalts,  thus  setting  at  rest  a  doubt  which  had  arisen  as  to  whether 
or  not  the  precipitated  gold  might  be,  to  some  extent,  re-dissolved  by 
remaining  for  many  hours  in  contact  with  the  solution  of  iron  per- 
salts. 

The  issue  of  a  patent  for  the  use  of  any  chemical  so 
well  known  to  contain  a  dissolving  agent  for  gold,  to  be 
used  under  patent  rights  as  the  essential  point  in  a 
process  for  dissolving  gold,  is  another  instance  of  the 
peculiarities  of  patent  grants.  From  this,  and  preceding 
patents,  it  is  reasonable  to  suppose  that  any  one  taking 
one  of  the  standard  chemistries,  Bailey's  pocket  book  of 
chemical  formula,  Storer's  dictionary  of  solubilities,  &c., 
could  go  through  the  entire  list  of  solvents  until  .the 
chemistry  of  each  was  exhausted,  and  obtain  from  the 
Patent  Office  exclusive  rights  to  use  them  for  the  pur- 

*  "Leaching  Gold  and  Silver  Ores,"  by  0.  H.  Aaron,  page  119. 


162  Remedies. 

poses  stated  in  these  books  ;  also,  judging  from  the 
inference  which  may  be  drawn  from  the  record  of  this 
long  list  of  protected  "  inventions,"  it  is  in  no  way 
necessary,  in  order  to  satisfy  the  Patent  Office  autho- 
rities, to  embody  any  explanation  of  method  or  con- 
trivance whereby  any  such  chemical  may  be  practically 
rutilized  outside  a  laboratory,  or,  indeed,  in  many  cases, 
inside. 

PROCESSES  IN  GENERAL  WORK. 

The  list  of  solvent  processes  having  been  gone  through, 
the  question  must  suggest  itself  to  the  reader,  how  have 
all  these  patents  progressed,  and  where  are  they  practi- 
cally applied  ?  To  this  question  there  is  but  one  answer, 
viz.,  that  out  of  this  long  list;  only  two  methods  are  in 
general  use  to  day. 

The  first,  is  the  method  which  was  devised  by  the  old 
Oerman  chemists  forty  years  ago,  and  which  has  since 
been  used  extensively,  with  most  trifling  modifications, 
in  nearly  all  gold  producing  countries ;  the  process  of 
working  is  so  amply  described  by  Kustel  (abstracts  on 
pages  105-113)  that  further  reference  is  unnecessary. 

The  other  method  is  the  Newbery-Vautin,  which 
simplifies  and  accelerates  the  older  process  known  as 
"  Plattner's."  The  Newbery-Vautin  method  is  the  out- 
come of  efforts  to  solve  the  problem  of  the  Mount 
Morgan  ores,  which  up  to  the  date  of  the  inauguration 
of  the  process  had  baffled  all  efforts  at  treatment.  From 
its  establishment  at  Mount  Morgan,  Queensland,  in 
1885,  it  has  treated  most  successfully  all  the  ore  from 
that  mine  ;  a  quantity  approaching  one  hundred  thousand 
ions,  producing  gold  to  a  greater  value  than  one  million 
sterling.  The  plant  at  the  Mount  Morgan  mine  is  now  of 
^sufficient  capacity  to  treat  1500  tons  weekly.  The  other 


Remedies.  163 

plants  in  Queensland  are  :  At  Norton,  a  100-ton  plant ; 
at  Ravenswood,  a  100-ton  plant;1  at  Cloncurry,  a  250- 
ton  plant.1  In  Victoria:  At  Sandhurst  Customs  Works, 
where  about  60  tons2  of  ore  from  every  part  of  Australia 
is  treated  weekly  ;  at  the  Long  Tunnel  Mine,  Walhalla, 
a  50-ton  plant.2  In  New  South  Wales  ;  At  Cunningar, 
a  50-ton  plant ;  at  the  Ironclad  Mine,  Ashburnham 
County,  a  50-ton  plant.2  In  New  Zealand:  At  Thames, 
a  250-ton  plant.1  In  the  United  States  :  At  Denver, 
Colorado,  a  250-ton  plant.1  In  Brazil:  At  the  "  Morro- 
Velho  "  Mine  of  St.  John  Del  Rey  Company,  a  50-ton 
plant.3  In  British  Columbia  :  At  Vancouver,  a  50-ton 
plant.1  In  South  Africa :  At  Johannesburg,  a  100- 
ton  plant ;  at  Barber  ton,  a  50-ton  plant.  In  Hungary  : 
at  the  Government  works  at  Nagy-Banya,  a  50-ton 
plant.1  And  in  London  a  100-ton  plant1  at  the  Central 
Works,  Regent's  Canal,  E.G.,  to  which  ore  is  sent  for 
treatment  from  all  parts  of  the  world. 

The  working  of  the  process  is  so  simple  that  an  ex- 
planation is  hardly  necessary  ;  the  patent  records  (pages 
150-1)  show  the  form  of  the  plant.  Instead  of  carefully 
damped  ore  being  placed  in  vats,  and  chlorine  gas  being 
passed  into  them,  sulphuric  acid  and  water  and  ore  are 
dumped  into  a  barrel ;  chloride  of  lime  is  then  put  in  and 
the  barrel  is  closed ;  air  is  then  pumped  in  to  a  pressure 
of  60  Ib.  to  the  square  inch,  or  over  ;  the  barrel  is  then 
revolved,  the  chemicals  coming  into  contact  evolve 
chlorine  gas,  which  is  by  the  pressure  retained  in  the 
water  and  forming  a  strong  dissolving  solution, 

1  Constructed  by   Messrs.    Charles   Appleby  and  Co.,    89,    Cannon- 
street,  London. 

2  Langlands  Foundry,  Melbourne. 

3  Messrs.  Robey  and  Co.,  Globe  Works,  Lincoln. 

Note  :  In  every  case  the  capacity  of  plant  is  for  weekly  output. 


164  Remedies, 

the  attrition  in  the  barrel — as  in  all  other  methods  of 
agitation — also  facilitates  rapid  chlorination,  and  in  a 
time  varying  from  half  an  hour  to  two  hours,  according 
to  the  coarseness  of  the  gold,  the  chlorination  is  com- 
pleted and  practically  all  the  gold  contained  dissolved. 
The  barrel  is  emptied  into  a  leaching  vat  underneath,  and 
by  the  aid  of  an  intermittent  vacuum  jigger  rapid  leach- 
ing is  effected.  The  liquor  is  passed  through  a  charcoal 
filter  and  the  chloride  decomposed,  the  gold  being 
deposited  upon  the  charcoal,  which  in  turn  is  burned,  the 
ashes  fused  with  borax,  and  the  metallic  gold  obtained. 

The  manner  of  organization  of  this  Company  should  be 
of  public  benefit,  and  tend  to  make  clear  the  difficulties 
which  are  constantly  arising  in  the  treatment  of  gold 
ores.  As  every  practical  worker  knows,  complex  and 
novel  features  frequently  present  themselves.  When 
any  such  case  comes  to  the  works  of  this  Company 
(which  are  now  practically  in  all  parts  of  the  world), 
attempts  are  made  to  solve  it ;  if  successful,  particulars 
are  sent  to  the  Central  London  Office,  from  whence  they 
are  distributed,  for  the  guidance  of  workers,  to  the 
various  works  and  branches  wherever  established.  If  at 
a  branch  works  a  complex  question  cannot  be  solved,  a 
parcel  of  the  ore  is  sent  to  London,  where  it  is  treated, 
and  the  particulars  of  treatment  are  then  distributed. 
In  this  manner  a  widely  established  metallurgical  busi- 
ness should  prove  in  a  short  time  a  greater  factor  for 
scientific  advancement  than  a  lifetime  of  individual  work 
when  the  experience  is  restricted. 

LEACHING  RESIDUES. 

As  before  mentioned,  the  Newbery-Vautin  patents  are 
the  only  ones  which  endeavour  to  facilitate  this  most 


Remedies.  165 

important  step  in  chlorination.  In  many  cases  the 
"  Plattner "  method  is  inapplicable  to  ores,  owing  to 
their  containing  such  a  quantity  of  slimes  as  to  pre- 
vent liquids  percolating  through  them.  In  such  a  case 
the  Newbery-Vautin  vacuum  pump  works  rapidly  and 
effectively.  Mr.  Aarons — before  referred  to — in  his 
"Leaching  Gold  and  Silver  Ores,"  page  33,  mentions 
this  difficulty,  and  suggests  a  suction  pipe  in  the  follow- 
ing manner  (Fig.  24)  : 

In  cases  of  difficult  leaching,  nitration  may  be  facilitated  by  means 
of  a  suction  pipe.  This  is  simply  the  discharge  pipe  of  the  leaching 
vat,  made  of  stiff  hose  or  of  wood,  instead  of  soft  rubber  as  in  other 


cases,  and  extended  to  a  vertical  depth  of  from  6  ft.  to  25  ft.  The  hose 
near  its  lower  end  is  coiled  once  around,  as  in  the  accompanying 
diagram,  and  secured  by  a  piece  of  wire ;  or  a  re-curved  piece  of  lead 
pipe  may  be  inserted  in  the  end  of  the  discharge  pipe  ;  or,  again,  the 
end  may  be  immersed  in  a  cup  of  water,  although  this  plan  is  less  con- 
venient than  the  others.  The  object  in  either  case  is  to  prevent ^the 
entrance  of  air. 

This  method  would  no  doubt  be  an  improvement  over 
the  older  methods  of  simple  percolation,  where  the  ar- 
rangement of  the  plant  would  permit  of  a  considerable 
height  between  the  chlorinating  vat  and  the  precipitating 
vessel,  otherwise  it  would  be  inapplicable.  It  seems 
strange  that  a  vacuum  pump  did  not  suggest  itself.  A 


166  Remedies. 

simple  vacuum  pump  is  not  effective  with  many  ores, 
because  it  has  a  tendency  to  make  the  ore  settle  down 
into  a  compact  mass  in  the  vat ;  but  the  intermittent 
action  prevents  this  result. 

When  the  liquor  has  been  removed  from  the  vat  by 
filtration,  pumping,  &c.,  some  more  advanced  method 
than  simple  settling  is  necessary  to  remove  from  the 
water  the  finely  divided  metallic  particles  which  have 
been  reduced  from  chloride  by  some  precipitant.  Mr. 
Aaron's  remarks  on  this  point  (page  119)  are  as  follows  : 

Suspended  Gold. — By  taking  some  of  the  waste  liquor  from  the  gold 
tub,  filtering  twice  through  Swedish  paper,  and  then  smelting  the 
paper  with  litharge,  I  found  that  after  twenty-four  hours  settling,  there 
remained  gold  in  suspension,  equal  to  $1.00  in  value  for  each  ton 
of  ore  leached.  After  forty-eight  hours  I  still  found  one  half  that 
quantity. 

This  experiment  is  sufficiently  illustrative  of  the  fact 
that  a  very  long  rest  is  necessary  before  the  metallic 
particles  of  gold  will  separate  themselves  from  water  by 
gravitation.  The  use  of  a  charcoal  filter,  in  a  great 
measure,  obviates  this  difficulty,  but  it  also  creates 
others.  A  charcoal  filter  is  by  no  means  a  perfect 
method  of  taking  gold  out  of  solution.  It  is  more  than 
probable  that  in  a  very  short  time  both  the  vacuum  pump, 
for  filtration,  and  the  charcoal  filter  or  settling  vat  for 
separation,  will  be  entirely  superseded  by  a  centrifugal 
method  which  the  Newbery-Vautin  Company  are  now 
perfecting.  The  matter  is  not  sufficiently  far  advanced 
to  write  fully  on  the  subject,  but  it  is  in  operation  on  a 
small  scale,  with  most  gratifying  and  astonishing  results.* 

*  By  the  courtesy  of  the  Newbery-Vautin  Company,  the  author  has 
been  given  particulars  as  to  where  their  plants  are  at  work,  and  also 
made  aware  of  the  experiments  referred  to,  and  he  hopes  to  have  an 
opportunity,  at  some  future  time,  of  making  the  results  public. 


Free  Milling. 


CHAPTER  VI. 

FREE  MILLING. 

THOSE  who  read  the  foregoing  pages  must  not  be  led 
into  the  belief  that  chlorination  or  any  other  solvent 
process  should  be  applied  to  all  classes  of  gold  ores,  irre- 
spective of  their  nature,  and  that  any  such  method  is 
capable  of  remedying  all  ills  whatever.  This  would  be 
almost  as  great  a  mistake  as  that — for  so  many  ages  per- 
sisted in — of  applying  to  all  classes  of  ores  the  process  of 
crashing  and  amalgamating  while  subject  to  a  flow  of 
water. 

It  is  also  no  use  insisting  that  miners  should  work  on 
scientific  principles,  in  cases  where  the  additional  cost  of 
applying  these  principles  exceed  the  additional  value  of 
gold  extracted.  The  whole  object  of  the  miner  is  to 
make  the  industry  a  paying  one,  and  to  arrive  at  this 
result,  all  sources  of  loss  must  be  avoided  ;  therefore, 
rational  principles  are  those  which  should  be  studied. 

As  before  stated,  a  solvent  process  is  especially  applic- 
able to  refractory  ores,  and  those  wherein  gold  particles 
are  individually  minute.  In  reality,  ores  of  such  a  class 
are  found  in  far  greater  frequency  than  those  containing 
coarse  or  fine  gold,  but,  as  many  cases  occur  where  the 
employment  of  chlorination  would  mean  a  greater  increase 
in  cost  of  treatment  than  would  be  justified  by  the 
increased  return  obtained,  some  of  the  more  advanced 
methods  of  crushing,  concentration,  amalgamation,  &c., 


168  Free  Milling. 

will  be  mentioned.  In  many  instances  these  methods 
are  applicable,  especially  with  low  grade  ores,  where  a 
payable  percentage  of  the  gold  can  be  extracted  by 
simple  mechanical  means ;  it  is  then  often  better  to  lose 
a  proportion  of  the  gold  than  to  save  all  by  a  more 
expensive  chemical  method.  Again,  wherever  simple 
mechanical  means  will  extract  gold  from  ores,  it  is 
manifestly  unnecessary  to  apply  chemical  processes. 

When  endeavouring  to  deal  with  a  few  types  of 
machines  for  purposes  of  illustration,  it  is  not  desired  to 
put  forward  prominently  one  particular  machine  above 
all  others,  and  it  is  hoped  the  reader  will  understand 
that,  as  the  number  of  different  contrivances  for  treating 
ores  are  "  as  the  sands  of  the  sea  in  number,"  mention 
can  only  be  made  of  a  very  limited  few.  In  these 
matters  piracy,  intentional  or  unintentional,  is  far  more 
rife  than  in  the  subject  of  chlorine  just  dealt  with,  and  it 
is  a  matter  of  great  difficulty,  without  months  of  research, 
for  any  writer  to  avoid  overlooking  original  inventors. 

STAMPER  BATTERY. 

Until  a  very  recent  date  the  stamper  battery  was 
considered  to  have  reached  the  acme  of  perfection  as  a 
machine  for  crushing  quartz,  to  liberate  the  gold  en- 
closed ;  even  at  the  present  time,  by  many,  it  is  still  so 
regarded,  and,  writing  generally,  it  may  be  said  that  no 
goldfield  is  without  it;  that  is  to  say,  any  goldfield  that 
has  reached  the  dignity  of  having  machinery  on  the 
ground.  Writings  on  the  subject  of  the  stamper  battery 
have  almost  exhausted  all  that  can  be  said  or  written 
about  it,  but,  with  an  endeavour  to  avoid  the  too  hack- 
neyed forms  of  expression,  some  of  its  peculiarities  may 
be  herein  recorded. 


Free  Milling.  169 

To  work  a  stamper  battery  to  its  greatest  efficiency,  it 
is  necessary  to  have  as  an  adjunct,  some  stone-breaker  or 
other  machine  to  reduce  the  ore  to  sizes  as  small  as  com- 
patible with  economy ;  this  notwithstanding,  in  the 
majority  of  cases  all  the  work  except  rough  sledge- 
hammer breaking,  is  left  for  the  stamps  to  do  ;  in  any 
case  a  very  undesirable  condition  is  brought  about  by  the 
stamp  action  in  the  battery  boxes.  A  most  excellent 
form  of  illustration  appropriated  by  many  writers*  is, 
that  the  method  of  crushing  ore  should  be,  to  break  the 
envelope  surrounding  the  gold  and  liberate  the  latter, 
as  a  nut  is  broken  without  destroying  the  kernel.  If 
such  a  result  could  be  brought  about,  perfect  crushing 
would  be  attained.  An  exactly  opposite  effect  is  brought 
about  by  the  stamper  battery;  the  fall  of  the  stamp  crushes 
both  envelope  and  kernel  into  an  unrecognisable  mass, 
and  as  the  kernel  (gold)  is  so  exceedingly  malleable,  it  is 
speedily  beaten  out  very  thin,  and  into  it  are  driven  hard 
stone  particles.  Each  succeeding  blow  beats  this  thinner, 
and,  aided  by  the  hard  stone,  soon  succeeds  in  cutting  the 
kernel  into  minute  fragments — the  consequences  following 
such  a  state  have  been  already  described  in  the  chapter 
dealing  with  losses. 

In  addition  to  the  foregoing  action,  a  very  unsatisfac- 
tory sizing  of  the  crushed  material  occurs.  As  stamps 
are  dropped  into  a  sufficient  depth  of  water  to  keep  the 
material  in  the  battery-boxes  continually  surging,  the 
first  material,  when  the  stamp  is  raised,  to  be  again 
brought  between  the  shoe  and  die,  is  the  fine  water-borne 
stuff,  already  fine  enough.  As  before  explained,  the 
richest  portions  of  the  ore  are  invariably  the  softest,  and 
the  ore  always  breaks  at  the  line  of  the  least  resistance — 

*  Probably  first  used  by  Mr.  Melville  Attwood. 


170  Free  Milling. 

the  most  valuable  line,  that  of  the  gold  —  therefore  the 
formation  of  valuable  slimes  continually  follows  when 
reducing  hard  matrix  to  the  required  fineness,  and  the 
product  of  the  battery-boxes  is  a  pulp  of  all  sizes,  from 
the  impalpably  fine  stuff  that  discolours  water  to  the 
coarsest  grain  capable  of  being  forced  through  the 
screens. 

Some  years  ago  Mr.  A.  N.  Rogers  carried  out  a  series 
of  experiments,  extending  over  a  ten  days'  run  of  the 
Bobtail  Mill,  Gilpin  County,  Colorado,  as  to  the  relative 
sizes  of  crushed  pulp  passed  through  80-mesh  screens 
of  a  stamper  batttery.*.  Of  the  total  quantity  tested 
1.17  was  caught  by  a  40-mesh  sieve;  with  a  60-mesh 
sieve,  17.55  per  cent.  ;  with  an  80-mesh  sieve,  13.08  per 
cent.  ;  and  with  a  100-mesh  sieve,  10.33  per  cent.  ;  leaving 
a  balance  of  57.87  per  cent,  that  was  not  arrested  by  a 
100-mesh  sieve.  Though  these  results  may  appear  rather 
peculiar  and  contradictory,  they  can  be  accounted  for,  as 
every  practical  man  will  know,  by  the  leakage  which 
always  exists  in  the  screens  and  frames  regulating  the 
discharge  of  a  stamper  battery,  and  from  the  fact  that 
many  of  the  crushed  fragments  of  quartz  are  like 
splinters,  which,  when  borne  by  water,  may  easily  pass  end 
on  through  a  screen,  whereas  in  a  sieve  held  horizontally 
they  would  be  arrested. 

Engineering^  gives  as  the  result  of  Australian  experi- 
ments with  pulp  passed  through  a  2  5  -mesh  screen  : 

....  The  size  and  percentage  of  the  crushings  were  as  follows  : 
Grains  ^  in  diameter    ......    12  per  cent. 

_1_  01 

»  505)  55  ......        **•*•  55  55 

55  7'2~       55  V  ......        *-V 


55 


*  Trans.  Am.  Inst.  Min.  Eng.,  vol.  xi.,  p.  34 
t  26th  August,  1887. 


Free  Milling.  171 

From  the  action  of  the  stamper  battery  everything  tends  to  show 
that  had  the  experiments  been  proceeded  with  further,  much  of  the  47 
per  cent,  would  have  been  divisible  to  diameters  as  small  as  400 
or  even  500  to  an  inch. 

Professor  Egleston,  writing  on  the  action  of  stamp 
mills,  gives  the  following  :* 

In  order  to  reproduce  the  conditions  in  which  metallic  gold  is  found 
in  stamp  mills,  strips  and  pieces  of  gold  were  pounded  in  a  perfectly 
clean  mortar,  with  a  perfectly  clean  pestle,  in  as  nearly  as  possible  the 
same  conditions  as  they  would  be  in  an  ordinary  stamp  mill.  It  was 
found  that  when  the  stamping  was  done  under  water,  and  with  light 
blows,  and  only  for  a  short  time,  while  there  was  an  evident  increase 
in  the  difficulty  of  amalgamation,  the  gold  did  amalgamate  with  suffi- 
cient readiness  to  insure  that  the  most  of  it  would  be  caught  by  the 
mercury  after  a  prolonged  contact.  When,  however,  the  blows  were 
very  heavy,  and  the  pounding  continued  for  a  long  time,  so  as  to  flatten 
out  the  piece,  prolonged  contact  with  the  mercury  produced  only  a  very 
slight  amalgamation,  which  did  not  even  show  the  slightest  trace  even 
after  five  minutes,  and  was  only  partial  even  after  half  an  hour. 
Every  attempt  was  made  to  make  the  mercury  attack  this  gold  ;  it  was 
placed  directly  in  it  and  on  it,  but  the  quicksilver  rolled  over  and  over 
as  if  the  gold  had  been  so  much  sheet-iron.  Even  when  the  mercury 
had  commenced  to  adhere  to  the  gold,  it  was  in  a  very  few  minute 
spots,  which  did  not  spread  for  a  long  time.  When  a  piece  of  the  same 
metal  was  treated  with  acid  there  was  a  perceptible  difference  in  the 
rate  of  amalgamation,  but  it  was  still  very  slow,  too  slow  for  the 
amalgamation  of  an  ordinary  stamp  mill.  When  these  same  pieces 
were  annealed  they  amalgamated  immediately.  The  same  operation 
was  repeated  on  pieces  pounded  in  a  mortar  without  water  ;  the  amal- 
gamation took  place  even  more  slowly  than  before.  When  pieces  were 
cleaned  with  acid  they  amalgamated  about  as  slowly  as  the  pieces 
treated  under  water  which  had  not  been  cleaned.  It  took  a  much 
longer  time  to  produce  the  adherence  of  the  fine  globules  of  mercury, 
and  they  propagated  themselves  much  more  slowly.  In  every  case 
where  a  freshly-broken  edge  came  in  contact  with  the  mercury  it  was 
attacked  at  once,  showing  that  a  film  had  been  formed  which  pre- 
vented contact.  This  film  is  slowly  dissolved  by  acids  and  quickly 
dissipated  by  heat,  for,  when  they  were  annealed,  the  pieces  amalga- 
mated at  once.  The  same  results  were  obtained  when  the  gold  was 
beaten  on  a  dusty  anvil. 

*  Trans.  Am.  Inst.  Min.  Eng.,  vol.  xii.,  p.  383. 


172  Free  Milling. 

ROLLS. 

Numberless  other  machines  have  been  devised  for 
crushers,  some  greater,  others  lesser  failures  than  the 
stamper  battery ;  yet  to  .this  day  the  machines  that,  to  a 
reasonable  extent,  supply  the  requirements  of  effective 
and  economical  crushers  can  be  counted  on  the  fingers  of 
one  hand.  In  choosing  a  machine  several  considerations 
should  be  taken  into  account :  locality,  cost  of  transit, 
facilities  for  erection,  water  supply,  physical  nature  of 
the  ore,  its  mineral  characteristics,  &c.,  and  the  effect 
produced  on  these  by  the  crushing  mill.  For  instance,  at 
the  Mount  Morgan  Mine  the  stamper  batteries  origi- 
nally erected  there,  were  silent  for  the  greater  part  of 
some  years — years  of  drought — Krom's  rolls  were  adopted 
and  dry  crushing  resorted  to.  If  the  ore  had  been  clayey, 
or  very  tough  and  hard,  such  machinery  would  not  have 
been  so  particularly  suitable.  All  other  conditions  being 
suitable,  rolls,  to  a  great  extent,  do  not  produce  the  ill 
effects  found  to  result  from  using  stamps,  and  are  very 
excellent  and  effective  machines,  but  they  cannot  be 
utilised  effectively  everywhere  ;  or,  when  running,  worked 
unintelligently. 

HUNTING-TON  MILL. 

One  of  the  most  rational  crushing  machines  that  has 
been  devised  of  late  years  is  the  Huntington  Mill,  which 
seems  to  be  rapidly,  and  certainly  deservedly,  coming 
into  favour.  Comparison  with  the  stamper  battery  may 
perhaps  be  the  best  means  to  show  its  advantages.  The 
principle  on  which  it  acts  is  very  perfect,  it  being  a  cen- 
trifugal or  rotary  crusher  ;  in  point  of  cost,  it  may  be 
taken  that  to  obtain  a  machine  of  equal  capacity,  a 
stamper  battery  when  erected,  is  approximately  from  five 


Free  Milling. 


173 


174  Free  Milling. 

to  six  times  more  costly ;  the  power  necessary  to  run  the 
latter  is  about  60  per  cent,  more  than  with  the  Hunting- 
ton  ;  according  to  the  facilities  of  the  neighbourhood,  so 
varies  the  time  taken  to  erect  and  have  in  working  order 
a  stamper  battery,  but  it  is  no  uncommon  occurrence  for 
this  to  take  two  months  from  the  time  the  machinery 
arrives  on  the  ground,  whereas  with  no  facilities  beyond 
having  prepared  a  level  floor,  say  12ft.  wide  and  30ft. 
long — outside  figures — for  engine  and  mill,  the  Hunting- 
ton  may  be  running  and  saving  gold  within  twelve  hours 
of  its  arrival  on  the  ground  ;  much  less  water  is  required 
to  work  it  effectively  ;  there  is  no  flouring  of  the  mercury 
from  being  pounded  up  by  the  machine  ;  and  breakages 
and  stoppages  are  reduced  to  a  minimum. 

The  accompanying  drawing  (Fig.  25)  show  the  construc- 
tion of  the  mill  so  clearly,  that  a  description  is  hardly  neces- 
sary. Taking  a  5 -ft.  mill — which  has  an  equal  output  to  a 
first-class  ten-head  stamper  battery— the  weight  complete 
is  4  tons  1 8  cwt. ;  the  power  necessary  to  drive  the  mill  at 
full  capacity  is  6  horse-power.  The  inside  diameter  of 
this  mill  is  5  ft. ;  four  suspended  rollers,  with  heads  1 6  in. 
in  diameter,  are  hung  from  the  framework,  when  the  mill 
is  revolved  they  fly  outwards  until  arrested  by  the  steel 
ring  forming  the  main  framework  of  the  mill,  and  around 
this  they  travel,  with  a  crushing  force  varying  with  the 
the  speed  ;  in  full  work  70  revolutions  per  minute  is  the 
speed  for  the  mill.  The  discharge  for  the  crushed  ore  is 
through  a  horizontal  screen  fixed,  for  half  the  circumfe- 
rence, just  above  the  main  steel  ring  or  crushing  band. 
The  rollers  are  slung  so  that  a  space  of  1  in.  always 
remains  between  them  and  the  bottom  of  the  crushing 
pan  ;  into  this  space  mercury  is  put.  Stirrers  are  fixed 
on  the  travelling  frame,  at  varying  distances  from  the 


Free  Milling.  175 

centre,  so  that  no  part  of  the  ore  in  the  pan  can  remain 
still ;  a  small  stream  of  water  from  a  hose  is  led  into  the 
pan  at  the  same  time  as  the  ore. 

For  the  effective  working  of  this  mill,  the  same  con- 
siderations should  be  observed  as  for  all  other  types  of 
crushing  machines  ;  the  mill  should  not  be  required  to  do 
sledge-hammer  work,  the  part  which  should  be  filled  by 
the  stone  breaker.  The  ore  should  first  pass  through  a 
stone-breaker  until  reduced  to  about  ^  in.  cubes,  then  a 
regular  feed  should  be  maintained ;  the  centrifugal  motion 
throws  outwards  against  the  crushing  band  all  the  heavier 
portions  of  the  ore,  in  contradistinction  to  the  lighter  and 
smaller  particles  of  ore  which  always  first  intervene  them- 
selves between  the  crushing  surfaces  of  a  stamper  battery ; 
as  explained  on  page  169.  The  mercury  is  not  beaten 
about  or  pounded  by  the  machinery,  consequently  the 
flouring  is  reduced  to  a  minimum.  The  rolling  action 
granulates  the  ore  more  than  pulverizes  it,  therefore 
the  sulphides  and  softer  parts  are  not  reduced  to 
impalpable  powder,  to  the  same  extent  as  in  most  ma- 
chines, and  are  consequently  in  good  condition  for  con- 
centration, and  much  of  the  free  gold  is  amalgamated 
inside  the  mill.  If  by  chance  a  nut,  bolt,  piece  of 
steel  drill,  &c ,  be  fed  into  the  machine  with  the  ore,  no 
injury  will  result,  because  the  rollers,  being  suspended, 
come  back  from  the  crushing  band  when  uncrushable 
material  intervenes  itself  between  them  and  the  surface 
on  which  they  roll — the  piece  of  steel,  from  being  con- 
tinually rolled,  would  be  soon  reduced  to  powder.  There 
is  one  very  important  feature  in  this  machine ;  the  gold 
is  rolled,  not  beaten  ;  on  this  question  Professor  Egleston 
writes  :* 

*  Trans.  Am.  Inst.  Min.  Eng.,  vol.  ix.,  p.  650. 


176  Free  Milling. 

The  pounding  action  of  the  stamp  has,  doubtless,  the  effect  to  make 
some  of  the  particles  of  gold  wholly  unattackable  by  the  mercury, 
while  the  action  of  rubbing  that  occurs  in  the  arrastra  is  much  more 
likely  to  pulverize  the  fine  particles  of  pyrites,  to  break  up  any  coating 
that  may  be  around  the  particles  of  gold,  and  rub  off  any  superficial 
deposit,  and  thus  bring  the  gold  into  contact  with  the  mercury  and 
make  it  amalgamate.  It  would  be  folly  to  advocate  the  re-introduction 
of  the  arrastra,  which  is  so  limited  in  its  output,  but  I  am  satisfied 
that  we  shall  have  to  come  back  to  its  principle.  It  is  a  very  remark- 
able fact  that  in  the  early  days,  Mexicans,  with  the  arrastra,  got  $50 
to  $60  per  day ;  the  stamp  mill,  working  on  the  same  rock,  obtained 
only  $15  to  $20,  and  instances  are  cited  where,  with  the  best  modern 
machinery  only  $20  to  $30  can  be  got  out  of  rock  which  yields  $700 
to  $800  by  fire  assay. 

The  reason  of  the  difference  in  these  results  is  fully 
explained  by  extracts  from  the  same  writer  on  pages 
48-9.  The  centrifugal  motion  of  the  rollers  in  the 
Huntingdon  mill  causes  a  constant  swirl  of  ore  and 
water  around  the  sides  and  against  the  screens ;  the 
discharge  is  therefore  very  good,  and,  from  this  cause 
also,  the  sliming  of  the  ore  is  reduced  to  a  mini- 
mum. The  work  of  the  mill  is,  comparatively,  noise- 
less, and  the  vibration  most  trifling.  Copper  plates? 
tables,  and  ripples  may  be  fixed  below  the  discharge 
plates  of  the  machine,  as  in  any  ordinary  crushing  mill ; 
also  in  addition  the  pulp  may  be  passed  through  classi- 
fiers, concentrators,  &c. ;  in  fact  the  difference  between  the 
Huntington  mill  and  the  methods  employed  for  treating 
ore  in  the  ordinary  wet  way,  is  solely  in  the  manner  in 
which  the  ore  is  crushed  and  discharged  ;  also,  that  a 
large  percentage  of  the  gold  contents  are  amalgamated 
inside  the  mill. 

Having  found  a  crushing  machine  most  economical  and 
most  suitable,  considering  the  ore  to  be  treated,  the  next 
requisites  are  classifiers  and  concentrators,  which  should 
also  be  considered  from  the  standpoint  of  the  nature  of 


Free  Milling.  177 

the  ore  ;  frequently  classifiers  are  omitted,  but  by  their 
use  more  perfect  results  are  obtained. 

CLASSIFICATION. 

The  most  economical  method  of  classification,  as  an 
adjunct  to  the  ordinary  gold  mill,  working  in  the  wet 
way,  is  where  the  water  already  carrying  the  ore  through 
the  machinery  is  utilized  as  the  classifying  medium;  other 
methods  mean  an  expenditure  of  power  in  removing  a 
large  bulk  of  ore,  not  generally  commensurate  with  the 
increased  return  obtained.  As  doubtless  every  one 
thoroughly  understands,  it  is  not  always  the  heaviest 
particles  which  fall  through  water,  while  the  lighter  are 
carried  away  by  the  stream;  most  generally  this  action  is 
regulated  by  the  extent  of  surface  the  particles  present  to 
the  surrounding  water,  and  the  action  resulting  from  rela- 
tive size  and  surface  is  frequently  more  asserted  than  that 
of  actual  gravity.  If  the  distinction  between  these  two 
causes  be  understood  it  will  be  readily  seen  that  to  bring 
about  comparatively  perfect  concentration,  sizing  or  clas- 
sification is  necessary  ;  then  gravity*  gets  a  chance  of 
making  itself  useful  in  .separating  mineral  from  rock, 
earth,  &c.  Coarse  classification  is  most  economically 
carried  out  by  jigs,  screens,  and  trommels,!  but  when  fine 
classification  is  needful,  machines  embodying  the  spitz- 
lutte  principle  are  the  best.  This  arrangement  generally 
takes  the  form  of  a  number  of  inverted  pyramidal-shaped 
boxes  increasing  in  size.  Into  the  smallest  compartment 
the  ore  is  fed  from  the  top,  while  a  stream  of  water  is 
brought  in  from  the  point  of  the  box  below,  through 
which  particles  heavy  enough  to  resist  the  stream  fall ; 

*  See   J.    C.   Bartell's  paper,   iu  the  Trans.  Am,  Inst.   Min.  Eng., 
vol.  vi.,  p.  415,  where  the  subject  is  treated  mathematically. 
f  Circular  screens. 

N 


178  Free  Milling. 

the  overflow  of  water  and  ore  from  the  small  box  goes  to 
one  larger,  where  it  is  there  treated  similarly,  until  when 
it  reaches  the  largest  size  the  upward  flow  of  water  is 
almost  imperceptible ;  in  these  machines  the  upward 
force  of  the  water  asserts  its  influence  on  pieces  present- 
ing the  largest  surface,  allowing  smaller  pieces  frequently 
of  less  weight  to  fall  through.  Perhaps  the  most  efficient 
classifier  yet  introduced,  is  that  devised  for  treating  the 
copper  ores  of  Lake  Superior,  described  by  Professor 
Richards  at  a  meeting  of  the  American  Institute  of 
Mining  Engineers.*  The  machine  works  on  the  prin- 
ciple above  described,  but  is  a  long  trough,  narrow  where 
the  ore  is  fed  into  it,  and  wide  at  the  delivery  end ;  the 
bottom  is  divided  into  V-shaped  compartments  rising 
half  way  up  the  sides  of  the  trough ;  into  the  bottom  of 
each  V  a  pipe  is  led  supplying  an  upward  stream  of 
water.  The  ore  is  carried  down  the  trough  by  a 
current  of  water  and  concentrated  in  its  passage 
by  the  obstructions  caused  by  the  tops  of  the  V-shaped 
compartments  ;  that  w^hich  falls  into  each  V  is  there 
classified  by  the  stream  of  water  led  into  the  bottom. 
When  some  such  sizing  operation  is  carried  out  sub- 
sequent concentration  of  the  material  is  much  more 
effective.  Any  one  requiring  further  particulars  oi 
classification  will  find  a  vast  amount  of  information  in 
the  writings  of  Rittinger. 

CONCENTRATORS. 

One  of  the  most  perfect  machines  for  concentration  yet 
devised,  is  the  Frue  Vanner.  The  plan  and  the  following 
description  of  the  machine  are  taken  from  the  latest  cata- 
logue of  Messrs.  Fraser  and  Chalmers.  (Fig.  No.  26.) 

*  Trans.  Am.  Inst.  Min.  Eng.,  vol.  xi.,  p.  231. 


Free 


The  Frue  Vanning  Machine:  This  is  the  most  successful  machine- 
ever  put  upon  the  market  for  treating  ores  direct  from  the  stamps,  or 
tailings  from  the  copper  tables  of  gold  mills.  It  is  an  endless- 
inclined  rubber  belt,  supported  by  rollers  so  as  to  form  a  plane 
inclined  rubber  surface,  4  ft.  wide  by  12  ft.  long,  and  bounded  on  the 
sides  by  rubber  flanges.  The  belt  travels  up  the  incline  and  around 
a  lower  drum,  which  dips  into  a  water  tank  where  mineral  is  collected. 
In  addition  to  the  travel  of  the  belt,  the  latter  receives  a  steady 
shaking  or  settling  motion  from  a  crankshaft  along  one  side,  the  shake- 
being  at  right  angles  to  inclination  and  travel  of  belt.  The  ore  is  fed 
on  in  a  stream  of  water,  about  3  ft.  from  head  on  belt,  and  flows* 
slowly  down  the  incline  subject  to  the  steady  shaking  motion,  which 
deposits  the  mineral  on  the  belt.  At  the  head  of  the  belt  is  a  row  of 
water  jets.  The  slow  upward  travel  of  belt  brings  up  the  deposited! 
mineral,  and  the  water  jets  wash  back  the  lighter  sand,  letting  only 


Fiq.  26. 

the  heavy  mineral  pass  and  be  deposited  in  the  water^taiik  below. 
The  endless  belt  has  been  long  known,  but  the  side  shaking  motion  and 
rubber  belt  used  in  the  Vanner,  makes  an  entirely  different  machine 
enabling  a  separation  to  be  made  more  perfect  than  with  any  other 
machine,  owing  to  the  small  inclination  of  belt  necessary  (from  J  in.^ta 
^  in.  to  the  foot),  and  very  much  less  water  than  was  ever  before 
possible.  .  .  .  The  Yanner  is  not  adapted  to  all  ores,  and  is 
unnecessary  where  close  saving  is  not  of  importance. 

When  treating  ores  in  the  usual  free  milling  manner, 
the     concentrator    employed    should,    for    purposes     of 
economy,   work   in  the  wet  way,  as  with  the  classifier 
previously  referred   to,  because   the    ore   when   passing 
through  the  mill  is  carried  along  by  the  stream  of  water, 


180  Free  Milling. 

and  if  once  allowed  to  remain  steady  it  would  lose  the 
momentum  of  the  water,  fall  to  the  bottom,  and  require 
a  fresh  expenditure  of  power  to  again  set  it  moving.  In 
many  cases  the  cost  of  a  second  moving  would  mean  the 
difference  between  profit  and  loss  ;  in  any  case,  because 
of  the  comparatively  small  proportion  the  richer  parts  of 
gold  ores  bear  to  the  whole,  a  relatively  extravagant 
expenditure  would  be  required  to  again  set  this  inert 
mass  in  motion.  Although  the  Frue  Vanner  has  reached 
a  generally  acknowledged  degree  of  perfection,  it  must 
remain  defective  on  account  of  the  inseparable  conditions 
ordinarily  presented  by  the  crushed  material  passing  over 
it.  All  this  material  derives  its  motion  from  the  water 
with  which  it  is  mixed ;  some  of  the  pulp  is  water-borne, 
the  remainder  is  pushed  along  by  the  water,  and  it  is  the 
particles  that  resist  the  action  of  the  water  and  remain 
on  the  travelling  belt  that  are  collected.  No  machine 
yet  introduced  for  the  treatment  of  gold  ores  has  suc- 
ceeded in  saving  float  gold  and  valuable  water-borne 
slimes.^ 

By  using  a  classifier  and  concentrator,  the  greater 
quantity  of  earth,  rock,  and  worthless  portions  of  the 
ore  will  be  washed  away,  and  the  bulk  so  reduced,  that 
the  cost  of  subsequent  treatment  by  amalgamation  or 
other  method  will  be  brought  within  remunerative  limits, 
in  many  cases  where,  otherwise,  the  margin  of  profit 
approaches  a  vanishing  point. 

AMALGAMATORS. 
Although  the  history  of  amalgamators  is  almost  as  old 

*  Some  astonishing  results  in  this  direction  are  predicted  by  inves- 
tigations of  Messrs.  Newbery  and  Yautin  into  separation  brought 
about  by  centrifugal  action. 


Free  Milling.  181 

as  that  of  crushing  mills,  there  is  not  yet  to  be  obtained 
a  really  perfect  amalgamator.  Few  patterns  are  wholly 
bad,  as  are  many  other  machines  daily  used  in  the  treat- 
ment of  gold  ores.  Perhaps  in  theory  the  most  perfect 
amalgamating  machine  yet  introduced  is  one  the  prin- 
ciple of  which  will  be  described  below.  *  It  is  most 
efficient  experimentally,  and  only  when  put  to  practical 
use  difficulties  begin  to  show  themselves.  The  arrange- 
ment of  the  machine  is  as  follows  :  A  column  of  mercury 
some  30  inches  in  heightf  is  placed  in  a  vessel,  so 
arranged  that  the  ore  to  be  amalgamated  may  be  intro- 
duced through  a  hollow  spindle  below  the  column  of 
mercury,  through  which  it  has  to  rise.  The  idea  being 
that  all  gold  passing  through  with  the  ore  must,  from  the 
pressure  of  the  column,  amalgamate  with  the  mercury  in 
its  upward  passage.  Eliminating  all  such  causes  of 
prevention  as  those  mentioned  under  heads  A  4,  5,  6, 
and  B  3,  4,  5,  Losses,  the  gold  does  amalgamate,  but 
nevertheless,  a  heavy  loss  arises  from  an  entirely 
different  cause.  The  reason  of  this  loss  is  as  follows  : 
The  lighter  portions  of  the  ore  passed  through 
this  machine  flow  over  the  top  in  a  continual  stream, 
but  there  is  continually  remaining  on  the  surface  of  the 
mercury,  a  residue  of  heavy  irregularly-shaped  particles 
of  mineral  matter,  and  iron  from  wear  of  machinery. 
The  mercury  is  kept  on  the  boil  by  the  action  of  the 
ore  passing  through,  consequently  there  is  not  only  a 
splutter  on  the  surface,  but  the  ore  grains  are  con- 

*  The  patent  records  of  Great  Britian,  America,  and  Australia,  show 
that  this  principle  is  a  most  favoured  one,  judging  from  the  manner 
in  which  it  is  claimed  by  inventors  as  original,  so  all  names  in  connec- 
tion with  it  are  purposely  omitted. 

t  Evidently  a  favourite  height  of  column,  being  a  pressure  equal 
to  one  atmosphere. 


182  Free  Milling. 

•tinually  carrying  globules  of  mercury  into  the  floating 
residue.  Each  grain  of  mercury  carried  upward  is 
.globular,  the  grains  of  heavy  residue  irregular  in  shape, 
.so  consequently  they  act  as  a  valve  upon  the  mercury 
:grains  and  prevent  the  possibility  of  their  passing  back 
into  the  column.  The  result  is,  that  with  the  continuous 
.stream  of  ore,  and  eventually  accumulated  residue, 
passing  over  the  top  of  the  machine,  there  passes  an 
equally  continuous  stream  of  minute  mercury  and 
amalgam  globules,  as  described,  held  mechanically. 

In  looking  up  the  subject  of  amalgamators,  many 
interesting  particulars  and  devices  are  to  be  met  with 
-continually,  amongst  which  is  a  patent  specification  taken 
out  in  the  year  1783  by  "  Charles,  Baron  de  Chastel, 
citizen  of  Geneva,  now  residing  in  Grafton  Street,  in  the 
parish  of  St.  Anne,  Soho,  in  the  County  of  Middlesex. " 
This  old  machine  is  on  the  principle  of  the  older  Mexican 
arrastra  and  Chilian  mill,  and  really,  it  is  a  matter  of 
grave  doubt  whether  to  this  day  there  is  to  be  found  a 
much  better  amalgamator  than  the  machine  of  the 
Baron  de  Chastel.  A  few  excerpts  from  the  specifi- 
cation may  be  of  interest.  It  is  set  forth  : 

That  he,  the  said  Charles,  Baron  de  Chastel  ....  should  and  lawfully 
might  make,  use,  exercise,  and  vend  his  "  New  Constructed  Machine 
for  Separating  of  Gold  and  Silver  from  Earth,  Scoria,  and  Impurity s, 
by  means  of  Trituration,  Mercury  ,  and  Amalgams,"  within  that  part 
of  Great  Britain  called  England,  the  Dominion  of  Wales,  and  Town  of 
Berwick-upon-Tweed. 

After  the  general  preamble  of  the  specification,  a 
declaration  of  the  Patent  Office  is  appended  as  below  : 

Be  it  remembered,  that  on  the  same  Twenty-seventh  day  of  August, 
in  the  year  of  our  Lord  one  thousand  seven  hundred  and  eighty-three, 
the  aforesaid  Charles,  Baron  De  Chastel,  came  before  our  said  Lord  the 
King  in  His  Chancery,  and  acknowledged  the  Specification  aforesaid 
and  all  and  everything  therein  contained  and  specified,  in  the  form 


Free  Milling.  183 

above  written.  And  also  the  Specification  aforesaid  was  stampt  accord- 
ing to  the  tenor  of  the  Statute  made  in  the  sixth  year  of  the  reign  of 
their  late  Mstjestys  King  William  and  Queen  Mary  of  England,  and  so 
forth. 

Inrolled  the  Twenty-seventh  day  of  August,  in  the  year  above 
written. 

The  specification  then  continues  : 

SPECIFICATION  OF  THE  PRINCIPAL  MATERIALS  THAT  COMPOSE 

THE  ABOVE  MACHINE  AND  THEIR  EFFECTS. 

The  Baron  de  Chastel  will  not  -confine  himself  to  a  Specification 
which  tends  to  move  the  machine  to  be  constructed ;  it  is  a  matter 
absolutely  arbitrary,  depending  upon  the  locality  where  the  establish- 
ment is  to  be  formed ;  and  he  thinks  that  the  Plans  will  sufficiently 
demonstrate  of  themselves  the  means  that  he  has  made  use  of.  Neither 
will  he  limit  himself  in  the  manner  in  which  he  has  laid  down  the 
powers  of  motion.  It  may  be  produced  by  the  arms  of  a  man,  by  means 
of  water,  fire,  wind,  or  by  the  power  of  a  horse,  &c.,  &c.  It  imports 
little,  how  it  is  produced,  provided  that  the  means  made  use  of  are 
sufficiently  powerful.  He  will  neither  specify  in  what  manner  the 
water  may  be  procured  ;  that  also  is  arbitrary.  It  may  be  effected  by 
river  or  rivulets,  which,  by  means  of  small  pipes,  may  supply  the  water 
that  may  be  wanted.  In  towns,  where  every  house  is  supplied  with 
water,  it  will  be  easy  to  obtain  a  sufficient  quantity  to  proceed  in  the 
course  of  that  operation  which  this  machine  requires ;  wells  may  be 
sunk,  pumps,  &c.,  &c.  It  is  easy  to  comprehend  how  superfluous  it 
would  be  to  specify  all  those  articles  which  are  absolutely  arbitrary, 
and  which  enter  in  the  principal  of  this  Invention  only  as  collateral 
matter.  Here  it  is  then,  the  Baron  de  Chastel  thinks,  only  necessary  to 
specify  : 

FIGURE  27 
a  Brickwork. 
b  Joists  and  platforms. 
c  Cast-iron  bason. 
d  Freestone  newett. 
e  Freestones  which  surround  the  bason. 
f  Exterior  canal  cut  in  the  said  stone. 

g  Mills   of  cast  iron  and  their  trees,   the  pivots  of  which  are  sup- 
ported in  the  centre. 
i  Wooden  circle  with  its  laths. 
k  Iron  arm  which  conducts  the  mills. 
I  Tree  and  lanthorn. 

in  Black  tin  bason  fixed  upon  the  lanthorn. 
n  Pipes  which  carry  the  water  into  the  said  bason. 


184 


Free  Milling. 


Fig.  Z7. 


o  Pipe  fixed  to  the  bason  m  which  carries  circularly  the  water  upon 

the  nut  d  during  all  the  time  of  the  work. 
p  Oblique  aperture  in  the  bason  of  iron. 
q  Oblique  aperture  in  the  freestone  e. 
r  A  little  vault  in  the  said  stone  to  enable  it  to  reach  the  bason  i  to 

draw  off  the  amalgam  a. 
*  Small  bason  of  freestone. 
t  Concavity  in  the  said  bason. 
u  Perpendicular  aperture  in  the  said  bason. 
v  Canal  for  carrying  off  the  water  into  the  reservoir,  Fig.  28. 


FIGURE  28. 

a  Brickwork  which  serves  as  an  enclosure  to  the  reservoir. 
6  Octangular  Carpenter's  work  which  supports  the  freestones^. 
c  Freestones  or  water  conduit. 
d  Large  lavigator  with  its  bottom. 
e  Second  lavigator  without  bottom  with  its  Jaths. 
f  Large  cast-iron  plate  concave  in  the  centre,   laid   on  the  bottom  of 

the  lavigator  d. 
g  Cast-iron  broyard. 
h  Little  cast-iron  casement. 
t  Lever  to  move  the  broyards. 
k  Crosspiece,  which  supports  the  axle-tree. 


Free  Hitting. 


185 


Fig.  28. 


Canal  for  carrying  off  the  waters  and  to  rid  the  building  of  the 

mud. 

Space  around  the  lavigator. 
Aperture  for  drawing  off  the  water  from  the  lavigator  or  reservoir. 


The  particulars  given  in  the  specification  are  as  to  the 
material,  manner  of  constructions,  and  general  remarks 
about  the  machine ;  it  is  unnecessary  to  reproduce 
them,  as  the  reproduced  essential  parts  of  the  drawings 
give  ample  particulars.  Excerpts  from  directions  con- 
cerning procedure  are  as  follows: 

The  water  which  incessantly,  during  the  operation,  runs  circular  on 
the  side  newetts,  successively  carries  off  the  ashes  or  sands,  with  which 
they  are  loaden  in  the  bottom  of  the  basons,  and  this  undergoes  the 
grinding  and  amalgama  of  the  mercury,  which  care  must  be  taken  to 
place  in  the  basons  before  the  beginning  of  the  lavigation.  This 
operation  is  multiplied  till  the  lavigation  is  finished  or  the  amalgama 
taken  away,  when  the  mercury  is  sufficiently  loaden  with  metal. 

Fourth  Operation. — When  you  would  take  away  and  draw  off  the 
amalgama,  you  continue  to  let  the  water  flow  and  supply  it  without 
loading  the  newetts  with  ashes  or  sands,  the  mills  continually  turning. 
This  operation  finishes  to  pulverize  the  earthy  and  stony  particles 


186  Free  Milling. 

which  remain  in  the  bason,  the  water  clears  up,  and  the  mercury 
amalgamized  either  of  gold  or  silver  remain  at  the  bottom  of  the 
bason. 

Fifth  Operation. — When  the  water  is  clarified,  the  amalgama  is 
drawn  off  by  taking  away  the  spigot,  Fig.  1,  letter  c,  which  closes  the 
aperture  of  the  cast-iron  bason.  The  amalgamised  mercury  is  received 
into  a  portable  bason ;  you  empty  the  water  of  the  bason  into 
the  little  bason,  Fig.  27,  which  passes  through  the  canal  into  the 
reservoir,  Fig.  28  ;  if  any  other  part  amalgamized  escape,  they  precipi- 
tate themselves  in  the  concavity  of  the  little  bason,  Fig.  27.  In  short,  if 
any  of  the  rich  particles  escape,  they  are  carried  off  into  the  reservoir. 

Sixth  Operation. — When  it  is  intended  to  draw  from  the  great 
reservoir  all  the  particles  that  may  have  escaped  from  the  machines, 
you  will  proceed  in  the  following  mariner : — You  will  supply  and  clarify 
the  water  by  turning  the  broyards  all  the  while  ;  then  you  will  open 
the  aperture  marked  n,  Fig.  28,  in  order  to  draw  off  the  water,  and 
what  remains  at  the  bottom  must  be  taken  up  with  spunges  ;  then  the 
amalgamized  mercury,  with  gold  and  silver,  which  will  be  drawn  off  at 
the  bottom,  must  be  passed  through  the  skin,  as  well  as  that  of  the 
machines,  in  the  usual  and  known  manner,  to  be  afterwards  passed 
through  the  retort.  Remark,  this  operation  of  the  lam  and  retort  is 
customary,  and  does  not  enter  into  the  principle  to  be  explained  of  this 
new  invention. 

The  Baron  de  Chastel,  after  having  taken  great  pains  in  the  re- 
searches he  has  made,  after  having  been  at  great  expense,  together  with 
his  father,  to  detect  all  the  errors  of  the  ancient  mills  which  caused  so 
great  a  loss  of  precious  matter,  after  having  made  different  trials  and 
different  pursuits  and  experiments  upon  this  subject  in  the  Republic  of 
Geneva,  has  at  length  succeeded  in  the  construction  of  this  machine, 
which  promises  very  considerable  advantage.  After  its  first  construc- 
tion made  at  Geneva,  he  has  still  made  new  trials  and  improvements 
upon  this  invention,  and  has  made  considerable  additions  and  improve- 
ments and  essential  corrections,  of  which  he  here  has  given  a  Specifi- 
cation, so  that  he  believes  that  this  machine  is  now  actually  in  a  very 
high  perfection. 

The  foregoing  drawings  and  particulars  of  Baron  de 
Chattel's  machine  are  given  principally  to  show  how 
little  advance  has  been  made  in  this  direction  during  the 
past  one  hundred  years. 

There  are  numberless  amalgamators  before  the  public, 


Free  Milling.  187 

but  the  subject  is  too  vast  to  attempt  to  do  other  than 
touch  upon  it.  Those  readers  who  are  anxious  to  know 
more  of  the  infinite  variety  of  machines  devised  for  the 
purpose  of  bringing  gold  grains  into  contact  with  mer- 
cury, can  find  in  nearly  every  work  on  metallurgy,  pages 
devoted  to  drawings  and  particulars  of  individual  devices, 
and  in  the  printed  catalogues  of  modern  machinery 
manufacturers  the  subject  is  still  more  exhaustingly 
dealt  with.  There  is,  however,  one  noticeable  peculiarity 
with  amalgamators,  whether  they  be  Wheeler,  or  Berdan 
pans,  Chilian  mills,  arrastras,  &c.,  &c.,  that  good  records 
are  only  obtained  when  the  particular  machine  is  worked 
by  a  man  who  believes  in  its  superiority,  and  there  is 
hardly  a  machine  in  use  of  which  some  good  work 
cannot  truthfully  be  recorded.  Whatever  paradoxes 
this  statement  may  present,  its  true  elucidation  appears 
to  be,  that  conditions  are  frequently  favourable,  and  that 
individual  care  and  intelligence  are  devoted  to  obtain 
high  results.  ' 

Patents  have  been  taken  out  for  amalgamating  with 
molten  lead,  zinc,  &c. ;  as  far  back  as  1828  Boussingault 
used  a  lead  amalgamator.  The  methods  employed  may 
be  generally  described  as  follows :  to  pass  hot,  dry, 
pulverized  ore  through  a  column  of  molten  lead,  arranged 
as  the  mercury  in  the  amalgamator  first  referred  to ;  the 
metal  is  kept  in  its  molten  condition  by  the  application 
of  outside  heat.  Oxidation  of  the  amalgamating  medium 
being  prevented  by  hot  carburetted  hydrogen  or  carbonic 
oxide  gases  being  passed  through  the  metal  with  the 
ore.  Although  such  proposals  for  amalgamators  are  very 
tempting,  the  practical  difficulties  in  their  working  have 
so  far  proved  insuperable. 


188  Free  Milling. 

DRY  SEPARATORS. 

Several  forms  of  dry  separators  have  been  devised, 
patented,  and  introduced,  but  up  to  the  present  they  are 
not  in  general  use.  The  arrangement  of  many  of  these 
machines  is  excellent,  and  the  principle  which  they 
embody  is  certainly  sound.  It  is  a  matter  beyond  doubt 
or  argument  that  air  is  a  much  more  delicate  medium 
than  water,  wherewith  to  effect  separation,  for  fine  stuft 
which  would  be  almost  permanently  held  mechanically 
in  water  would  fall  with  comparative  rapidity  through 
air.  A  form  of  dry  concentration  not  generally  recog- 
nized is  that  which  takes  place  on  the  surfaces  of  tailing 
heaps.  Any  one  on  a  goldfield  may  notice  how  on  a 
windy  day  these  heaps  change  colour ;  this  is  because 
the  lighter  portions,  generally  rock  and  clay  particles,  are 
blown  away  and  the  mineral  matter  left  quite  exposed. 
For  this  reason  many  people  have  been  quite  misled 
as  to  the  value  of  tailings  heaps  by  taking  samples 
from  the  surface,  although,  otherwise,  the  sampling 
may  have  been  most  carefully  done.  For  all  reasons, 
in  order  to  obtain  correct  samples,  they  should  be 
taken  throughout  the  entire  depth  of  the  heap.  It  is 
to  be  hoped  that  Mr.  Krom's  endeavours  to  popu- 
larise dry  separators  will  bear  more  fruit  in  the 
future  than  in  the  past,  for  this  gentleman  is  an  inde- 
fatigable investigator,  and  to  the  result  of  his  labours 
may  be  credited  much  of  the  present  prominence  of  the 
question. 


Paragraphs.  189 


CHAPTER  VII. 

PARAGRAPHS. 

THERE  are  a  few  other  matters  of  interest  which  should 
be  briefly  referred  to,  and  as  they  do  not  come  under  any 
of  the  previous  heads  they  are  now  appended  indis- 
criminately. 

ALLUVIAL,  DRY  SEPARATING. 

Mr.  Charles  Phillips,  of  Melbourne,  has  patented  a 
most  ingenious  machine  as  a  dry  separator  for  use  at 
waterless  alluvial  diggings,  some  of  the  mechanical 
actions  noticeable  in  its  working  are  so  interesting  that  a 
description  of  the  method  may  perhaps  be  not  tedious. 
The  "  dirt"  passes  through  a  series  of  screens,  trommels, 
and  jigs,  by  which  the  stones  or  coarser  pieces  are  re- 
moved, the  remainder  falls  through  a  current  of  air  regu- 
lated to  suit  the  material,  and  the  dust  and  much  of  the 
worthless  matter  are  carried  off  in  the  same  way  as  chaff 
from  a  winnowing  machine.  The  residue  then  falls  on  to 
sloping  shaking  tables,  with  ridges  of  battens  crossing 
them,  something  like  the  ripples  in  a  wet  amalgamated 
plate.  The  only  necessity  now  remaining  to  ensure  almost 
perfect  saving,  is  that  the  gold  should  be  sufficiently  fine, 
for  if  coarse,  much  of  it  is  sure  to  be  lost  unless  very 
carefully  watched.  The  jigging  action  on  these  tables 
brings  to  the  bottom  the  finest  stuff,  quite  irrespective  of 
gravity,  and  the  mechanical  action  of  these  fine  particles 
raises  the  larger  portions,  also  quite  irrespective  of  their 


190  Paragraphs. 

gravity  (just  as  in  the  shaking  of  a  basket  of  apples  the 
large  ones  rapidly  come  to  the  surface),  and  so  they  roll 
down  the  tables,  and  may  be  thrown  away  as  refuse.  The 
more  impalpably  fine  the  gold,  the  more  certainty  there  is 
of  catching  it,  and  it  will  be  found  behind  each  ripple  on 
the  jigging  tables.  If  a  coarse  piece  of  gold  were  put 
into  the  stuff,  and  mixed  thoroughly,  when  the  stuff  is  put 
on  the  jigging  table,  the  piece  of  gold  may  be  seen  to 
gradually  show  itself  above  the  fine  residue,  then  get 
quite  on  the  surface  and  eventually  climb  over  each  ripple, 
until  it  rolls  off  the  end  of  the  table  with  other  large 
particles. 

SMELTING. 

Very  little  can  be  herein  said  about  smelting.  It  is  a 
subject  in  itself,  most  scientific,  elaborate,  and  yet  essen- 
tially practical.  It  is  doubtful  whether  any  process  yet 
known,  can  compete  successfully  with  smelting,  when  the 
conditions  of  work  for  the  latter  are  favourable  and 
economical ;  but  where  fluxes  have  to  be  purchased 
or  carried  for  long  distances,  it  can  in  no  way  compete 
with  many  other  methods.  The  remarks  of  Mr.  Rossiter 
W.  Raymond*  on  this  point  may,  with  advantage,  be 
quoted  : 

The  idea  of  smelting  the  ordinary  auriferous  quartz  (even  of  low 
grade)  has  been  put  forward  at  different  times  by  the  possessors  of 
patent  fluxes ;  but  its  absurdity  will  appear  if  we  reflect  that  every 
five  dollar's  worth  of  gold  in  a  ton  of  quartz  constitutes  but  one 
one-hundred-thousandth  part  of  the  whole  mass.  To  smelt  auriferous 
quartz,  therefore,  is  to  flux  and  remove  practically  100  per  cent,  of 
quartz.  The  case  is  different  when  the  barren  material  is  not  quartz, 
which  needs  a  base  before  it  will  flux,  and  still  more  widely  different 
when  the  ore  contains  some  other  useful  metals  besides  gold,  such  as- 
lead  or  copper.  .  .  . 

*  Raymond's  Reports,  1870,  p.  728. 


Paragraphs.  .      191 

ELECTRO-METALLURGY,  &c. 

A  variety  of  other  methods  for  the  separation  of  gold 
from  its  surroundings  have  been  from,  time  to  time  put 
forward,  such  as  the  Longmaid'  and  other  semi-smelting 
processes,  &c.,  also  processes  for  electrolysis.  Of  this 
latter  it  seems  that  Andrew  Cross  was  one  of  the  first 
investigators.  He  began  an  exhaustive  series  of  experi- 
ments in  1807,  and  carried  them  on,  and  wrote  much 
upon  the  subject,  until  his  death  in  1859.  Of  late  years 
the  method  has  been  revived  with  considerable  flourish 
of  trumpets,  but  it  may  be  said,  so  little  being  yet 
known  of  the  science  of  electro-metallurgy  that  no  such 
process  can  at  present  be  taken  into  economical  consider- 
ation ;  but  with  such  workers  as  Watt,  and  others  there 
is  ground  for  hoping  some  considerable  degree  of  advance- 
ment may  be  reached. 

HAULING  APPLIANCES. 

It  is  a  frequent  complaint  of  miners  that  the  wire 
ropes  supplied  by  manufacturers  are  of  bad  quality  and 
do  not  wear  for  any  length  of  time.  Though,  doubtless, 
wire  ropes  of  an  inferior  quality  are  sometimes  supplied, 
in  the  majority  of  instances  the  fault  may  be  traced  to 
causes  quite  apart  from  either  the  quality  or  the  manu- 
facture. It  may  be  remembered  that  on  page  47  the 
detrimental  effect  was  noted  of  acid  saline  waters  on 
gratings  through  which  pulp  is  forced ;  from  the  same 
cause  and  in  the  same  manner  these  waters  produce  a 
molecule  change  in  the  iron  or  steel  of  ropes,  and  render 
them  brittle.  Some  experiments  to  this  effect  were  as 
follows  :  A  piece  of  ordinary  non-galvanised  iron  tele- 
graph wire  was  taken  and  divided  into  lengths;  held  in  a 
vice,  any  of  these  lengths  would  stand  twenty  complete 


192  Paragraphs. 

turns  before  the  wire  would  break ;  some  of  the  lengths 
were  immersed  in  saline  water,  acidulated  with  sulphuric 
acid,  for  about  half  an  hour,  when  it  was  found  that  they 
would  break  before  one '  complete  turn  could  be  made. 
Then  if  the  wires  which  had  been  steeped  in  this  water 
were  heated  to  redness,  it  was  found  that  they  regained 
their  strength,  and  would  stand  the  previous  breaking 
twist.  Some  wire  ropes  are  manufactured  with  a  piece 
of  tarred  hemp  laid  down  their  centre ;  this  greatly  facili- 
tates the  injurious  effect  of  sulphuric  acid  and  saline 
waters,  the  tar  in  the  hemp  is  soon  dissolved  out  by  the 
action  of  the  acid,  and  the  hemp  becomes  a  sponge  to 
hold  the  liquid  in  contact  with  the  metal.  It  is  usual  in 
mines,  to  coat  the  ropes  with  a  mixture  of  tar  and  grease, 
but  if  great  care  is  not  taken  to  keep  this  protecting 
medium  complete,  where  such  waters  occur,  they  speedily 
manifest  their  deleterious  effect.  A  very  simple  experi- 
ment will  prove  whether  the  explained  actions  have 
brought  about  the  breaking  of  wire  ropes,  therefore  any 
disagreement  bet  ween  miners  and  machinery  manufactures 
on  this  point,  may  easily  be  settled. 


INDEX. 


Aaron's  Researches,  161,  166 

Acidulated  Water,  Evil  Effects,  31,  46,  47,  48,  49,  191 

Action  of  Stamp  Mills,  Professor  Egleston  on  the,  171 

Air  Pressure  in  Chlorinating  Barrel,  146,  149,  153,  158 

Air  Supply  to  Calcining  Furnaces,  96 

Alloys  of  Gold  and  Arsenic,  Mr.  J.  C.  Newbery's  Notes  on,  100 

Alluvial  Deposits,  12 

Alluvial,  Dry  Separating,  189 

Alluvial  and  Hydraulic  Mining,  Improvements  in,  27 

Amalgamator,  Baron  de  Chastel's,  182 

Amalgamators,  180 

Antimony  in  Quartz  Veins,  61 

Arrastra,  Professor  Egleston  on  the,  176 

Arsenic  in  Quartz  Veins,  Mr.  J.  C.  Newbery  on,  61 

Atmospheres  incapable  of  sustaining  Combustion,  96,  97 

Atomic  Weight  of  Gold,  3 

Atwood's  Investigations,  59 

Bagration,  Prince  Pierre,  Dissolving  Gold  by  Cyanide  of  Potassium,  68 

Barrel  Chlorination,  First  Attempt,  75,  76 

Bismuth  in  Quartz  Veins,  61 

Brittle  Gold,  100 

Bromine  and  Iodine  Combinations,  5 

Calvert,  F.  Grace,  F.R.S.,  Paper  read  at  the  British  Association  on  the 

Chlorination  of  Gold  Ores  by,  127 
Charcoal  Decomposing  Gold  Chloride,  146,  147,  148 
Chinamen,  their  Practices,  43,  49 
Chloridizing  Roasting,  98,  100 
Chloridizing  Roasting,  Mr.  Stetefeldt  on,  101 
Chlorination,  General  Remarks  on,  93 
Chlorination  Mill  for  Treating  the. Concentrates  from  the  Frue  Vanners, 

113 

Chlorination,  Natural,  8,  9,  10 
Chlorination  Works  at  Reicheristein,  Silesia,  88 


194  Index. 

Chlorine  Combinations,  5 

Chlorine  Gas,  Dry,  68,  142 

Chlorine,  Gaseous,  first  used  for  extracting  Gold,  82 

Chlorine,  Manufacture  of,  6 

Chlorine,  Production  of,  6,  7,  8,  9,  10 

Classification  at  Gold  Mills,  177 

Classifier  for  Treating  Copper  Ores  at  Lake  Superior,  178 

Clayey  Ores,  Gold  held  in  Suspension  by  Action  of  Muddy^1  Waters,  44 

Cobley,  Thomas  Henry,  Obtaining  Gold  from  Auriferous  Quartz,  <fcc., 

by  Ohlorination  and  Precipitation,  129 
Cobley  and   Wright,    Messrs.,  Extracting  the  Gold   and   Silver  from 

Auriferous  and  Argentiferous  Ores,  120 
Collection  of  Gold  in  Ancient  Egypt,  21 
Concentrators,  178 

Conversion  of  Iron  into  Ferric  Oxide,  97 
Cost  of  the  Chlorination  Process  per  Ton  of  Ore,  113 
Cost  of  Treating  Pyrites,  57 
Coster's  Experiments,  72,  75,  76 

Crookes,  William,  Treatment  of  Gold  by  Perchloride  of  Iron,  159 
Cross's  Experiments  on  Electro-Metallurgy,  191 
Crushing  Free  Milling  Ores  at  Sandhurst,  Yictoria,  39 
Crystallography  of  Gold,  4,  13,  19 
Cyanides,  Use  of,  5,  68,  144,  148,  149 

Dahne,  F.  W.,  Extraction  of  Gold  by  "liquid"  Chlorine,  128 

Decomposition  of  Pyrites,  7 

Decomposition  of  Pyrites  by  Roasting,  Remarks  on,  94,  95 

"  Deep  Leads,"  13 

Deetken,  Gustavus  F.,  Extracting  Gold  from  Pyrites,  104,  122 

Deetken,  Gustavus  F.',  Introduction   of  the   Chlorination   Process   into 

Nevada,  California,  by,  104 
Deetken's  Tests,  45 

De  Figaniere,  A.,  Dissolving  Gold  by  Bromine,  137 
De  Lacy,  A.  0.  L.,  Extraction  of  Gold  and  other  Metals  from  Mineral 

Substances,  123 

Demonstration  of  Gold  held  in  Suspension  by  Water,  54 
Density  of  Gold,  3 
Deposits  of  Gold,  Depth  of,  13 
Deposits  in  the  Matrix,  14 

Destroying  the  Pyrite  Envelope,  Mr.  Latta's  Method  of,  57 
Dry  Crushing,  35 

Dry  Separator  for  Waterless  Alluvial  Diggings,  Mr.  0;  Phillips's,  189 
Dry  Separators,  188 


Index.  195 

Ductility  of  Gold,  4 

Buffos',    Dr.,    Experiments     on   the     Extraction    of    Gold   from  'the 

Reichenstein  Arsenical  Residues,  72,  73 
"Dust  Gold,"  12,  40 

Effect  of  the  Stamper  Battery  in  Crushing  Ore,  169 

Egleston's  Remarks,  48,  49,  176 

Electro  Metallurgy,  &c.,  191 

Eisner,     L.,     Separation    of    Gold    from     Arsenic    and    Tin   by  Dry 

Chlorine  Gas,  68 

Engineering  on  the  Australian  Mining  Practice,  42,  170 
Evans,  Nelson  Frederick,  Treatment  of  Gold  Ores  by  Chlorination,  138 
Experiment  by  Messrs.  J.  C.  Newbery  and  C.  Vautin,  37 

Films  of  Air  on  Quicksilver,  R.  W.  Raymond  on,  50 

Filtration  Hastening,  147,  165 

Fine  Gold  attached  to  Pieces  of  Rock  and  carried  into  Tailings,  43,  59 

Fine  Gold  held  in  Suspension  by  Air,  at  Mount  Morgan,  35 

Fine  Gold  held  in  Suspension  by  Water  and   carried   Down  Stream,. 

32,  53 

"Float"  Gold,  35,  38,  40,  41,  42,  43,  44,  51 
Fluxes,  190 

Formation  of  Films  which  Prevent  Amalgamation,  4  7 
Formation  visible  on  Goldfields,  8 
Formation  of  Lodes,  Observations  on  the,  9 
Forms  and  Sizes  of  Gold,   12,  15 
Free  Milling,  167—188 
Free  Milling  Ores,  29 
Frue  Vanner  Concentrator,  The,   178 
Furnaces  Unsatisfactory,  96 
Fusing  Point  of  Gold,   3 

Galena,  The  Effect  of,  in  Calcining,   98 

Galvanic  Action  in  Batteries,   45 

Georgi's   Treatment  of    the   Reichenstein  Arsenical  Residues    by   the- 

Chlorination  Process,  83 
Gold  with  Antimony,  61,  100 
Gold  with  Arsenic,  61,  100 
Gold  with  Bismuth,  62 
Gold  in  Boiler  Scale,  35 

Gold  Carried  away  by  Muddy  Battery  Water,  44 
Gold  Dust  Collected  in  South  Africa  from  "Blanket "  Formation,  40 
Gold  Dust  in  the  Sea  Sands,   14 
Gold  in  Gossan,  9 


196  Index. 

Gold  with  Lead,  62 
Gold  in  Mine  Timbers,  38 
Gold  Miners'  Practice  Forty  Years  Ago,   22 
Gold  with  Oxide  of  Iron,  8 
Gold  Passing  through  Felt  Filter,  39 
Gold  Precipitated  in  Water  Tank,   42 
Gold  in  Pyrites,  6,  15,  55 
Gold  in  Sea  Water,   19 
Gold,  Solvents  for,  5 

Gold  on  the  Thames  Field,  Mr.  W.  Skey  on  the  Reported  Loss  of,  47 
Gold-bearing  Patches  of  Stone,   16 

Gold-bearing  Pyritous  Ores,  Mr.  M.  Atwood's  Paper  on,    58 
Grass  Valley,  California,  41,  114 
Grease  in  Mills,  The  Effect  of,  48 

Guettler,  Wilhelm,  Obtaining  Gold  from  the  Arsenic  Ores  by 
Solvent  Process,  85 

Hannay,  James  Ballantyne,  Obtaining  Gold  from  Refractory  Ores 
by  Chlorination,  144 

Hardenburg  on  Free  Milling,  52,  53 

Hardness  of  Gold,  3 

Hargreaves,  James,  Thomas  Robinson,  and  John  Hargreaves,  Treat 
ment  of  Pyrites  to  obtain  the  Sulphur  and  Valuable  Metals 
therein,  142 

Hauling  Appliances,   191 

Henderson,  William,  Treatment  of  certain  Ores  and  Obtaining  Pro- 
ducts therefrom,  115 

Hill  End  Mine,  near  Sydney,  The,   16 

Huntingdon  Mill,  The,   172 

Impure  Mercury,  The  Effect  of,  49 

Introduction,  1 

Iodine  and  Bromide  Combinations,  5 

Karsten's  Suggestions  as  to  use  of  Gaseous  Chlorine,  82 
Krom's  Dry  Separators,  188 

Lange's,  Experiments  on  the  Treatment  of  Reichenstein  Arsenical  Resi- 
dues by  Chlorine,  77 
Latta's  Investigations,  55,  56,  57 

Leaching  Residues,  The  Newbery-Vautin  Patents  for,  164 
Lead  in  Amalgam,  The  Effect  of,  62 
Lead  Amalgamator,  Boussingault's,  187 
Liebius'  Investigations,  36,  37 


Index.  197 

List  of  Inventors  of  Solvent  Processes,  67 

Long  Tunnel  Mine,  58 

Loss  of  Mercury  through  Excessive  Stamping,  50,  64 

Losses,  29 — 65 

Losses  of  Gold  in  Free  Milling  Ores,  30 

Losses  of  Gold  in  Refractory  Ores,  31,  53 

Losses  of  Mercury,  32,  64 

McArthur,  John  Stewart,  Robert  Wardrop  Forrest,  William  Forrest, 

and  George  Morton,  Obtaining  Gold,  Silver,  and  other  Metals  from 

Ores  by  Chlorine,  Bromine,  Iodine,  &c.,  143 
McArthur,    John    Stewart,    Robert    Wardrop    Forrest,    and    William 

Forrest,    Obtaining  Gold  and  Silver  from   Ores  by   Cyanogen  or  a 

Cyanide  or  Cyanogen-yielding  Substance,  148 
McDougal's  Tests,  41 
Malleability  of  Gold,  4 
Mears,   J.  J.   Howell,   M.D.,    Treating    Gold    Ores    by    Chlorination, 

130,  137 

Mechanical  Effect  of  Heavy  Mineral  Particles  in  Ores,  63 
Mercury  affected  by  Grinding,  32,  50,  64,  65 

Microscopic  Examination  of  Gold  subjected  to  a  Blowpipe  Flame,  60 
Mine  Waters,  Experiment  by  Mr.  Newbery  on,  39 
Mines  of  Reichenstem  in  Silesia,  84,  85,  86,  87,  88,  89 
"Mining  Expert,"  The,  26 
Mining  Schools  and  Similar  Institutions,  26 
Mount  Morgan  Mine,  The  Plant  at  the,  162 
Mount  Morgan  Mine,  Queensland,  The,  16,  33 
Munktell,  Henrik,  Extracting  Gold  by  Means  of  Chlorine  from  Ores, 

Ac.,  138 

Natural  Alloys  of  Gold,  4,  15 

Natural  Laws,  66 

Newbery's  Investigations,  37,  39,  61,  62,  100,  101 

Newbery-Vautin  Company  Organisation,  164 

Newbery-Vautin  Chlorination  Process,  The,  38,  163 

Newbery  and  Vautin,  Improvements  in  Wet  or  Hydro-Metallurgical 

Method  of  Extracting  Gold  from  Auriferous  Material,  145 
Newbery- Yautin  Plants  at  Work,  List  of,  162 
Non-Amalgamation  of  Gold   through  Hammering,  Professor  Egleston 

on,  48 
Nuggets,  12 

Occurrences,  12  —  20 


198  Index. 

Old-time  Miners'  Appliances,  25 

Ore    rom   Mount  Morgan    Shipped  to    Germany,    England,    and   San 

Francisco,  35 

Ores,  Specimens  of,  at  the  International  Exhibition  of  1851,  85 
Ores,  Terms  Invented  for,  24 
Organization  of  the  Newbery-Vautin  Company,  164 

Paper  read  by  Mr.  G.  Latta  at  the  Royal  Society  of  New  South  Wales 

on  Gold  in  Refractory  Ores,  55 
Paper  read  by  Dr.  Liebius  at  the  Royal  Society  of  New  South  Wales, 

35 
Paper  read  by  Dr.  John  Percy,  F.R.S.,  tit  the  British  Association  on 

the  Extraction  of  Silver  and  Gold  from  Ores  by  Chlorine,  69 
Paragraphs,  189 — 192 

Partial  Decomposition  of  Sulphides,  The  Effect  of,  63 
Patents,  67,  101,  102,  115,  118,  120,  122,  123,  128,  129,  130,  137,  138, 
•   142,  143,  144,  145,  148,  149,  154,  159 
Paul's  Investigations,  41,  42,  44 
Phillips',  Charles,  Dry  Separator,  189 
Phillips,  J.  S.,  on  the  Chlorination  of   Gold   Ores  in  Revolving  Wood 

Barrels,  128 

Plattner,  Carl  Fredrich,  Chlorination  of  Gold  Ores,  70,  89 
"  Plattner  "  Chlorination  Process  Described  by  Kustel,  104 
Pollok,    James    Holms,    Extraction    of    Gold    by    Chlorine    from  Re- 
fractory and  other  Ores  and  Tailings,  154 
Primard,    Edouard,    Stamper    Battery     and    Kiln    and    Chlorination 

Process  for  Gold  Extraction,  102 
Principles  of  Collecting  Gold,  21 
Procedure  of  Late  Years,  Remarks  on  the,  21 — 28 
Processes  in  General  Work,  162 
Properties  of  Gold,  Some  of  the,  3—11 
Pyrites,  Gold  in,  6,  15,  55 

Quartz  Mining  in  California,  J.  Hardenberg  on,  52 

Rapid  Chlorination,  First  Attempt  to  Introduce,  120 

Raymond,  R.  W.,  on  Float  Gold  and  Amalgam,  51 

Raymond,  R.  W.,  on  Smelting,  190 

Refractory  Ores,  29 

Reichenstein  Deposits,  72,  73,  77,  78,  83,  84,  85,  86,  87,  88,  89 

Reichenstein,  Description  of  the  Works  at,  from  Kerl's  "  Hiittenkunde," 

88 
Reichenstein  Mines,  84,  85,  86,  87,  88,  89 


Index.  199 

Remarks  of  Jury  of  Exhibition  of  1851,  on  Chlorination,  86,  87 

Remedies,  66—166 

Richter,  Theodor,  Article  in  the  "  Journal   fur  Practisch  Ohemie"  on 

some  Experiments  on  Chlorination,  72,  83 
Roasting,  96 
Roasting  Gold  Grain,  60 
Roasting  Pyritous  Ores,  Mr.  Newbery  on,  96 
Rogers'  Tests  with  Stamper  Battery,  170 
Rolls  for  Crushing,  118,  172 
Rosales'  Workings,  58 

Samples,  Method  of  Taking,  188 

Schaeffer,  Charles  A.,  Dissolving  Gold  by  Bromine,  137 

"  Shotty  Gold,"  12 

Size  of  Grain  of  Gold,  4 

Sizes  of  Crushed  Pulp,  Experiment  on  the,  170 

Sizes  and  Forms  of  Gold,  12,  15 

Sizing  of  Crushed  Ore  in  Battery  Boxes,  Unsatisfactory,  169 

Skey's  Researches,  47,  48 

Skidmore  on  Float  Gold,  43 

Slimes  in  Battery  Sands,  Mr.  Deetken  on,  45 

"  Slimes,"  Composition  of,  55 

Slimes,  Production  of,  54,  55,  64,  65 

Smelting,  R.  W.  Raymond  on,  190 

Sodium  Amalgam,  61,  62 

Solubility  of  Gold,  5 

Solvent  Processes  in  General  Work,  162 

Solvents  of  Gold,  5,  10 

Spicker,  Charles,  Dissolving  Gold  by  Chlorine,  101 

Spitzlutte  Principle  for  Fine  Classification,  177 

Spring  Gully  Mine,  Queensland,  Experiment  at,  32 

Stalactitic  Formations,  Gold  in,  34 

Stamper  Battery,  168 

Stamper  Battery,  Losses  of  Gold  by  use  of,  49,  53,  169,  176 

Stetefeldt  on  Mears'  Process,  137 

Stetefeldt  on  Roasting  Ores,  101 

Stone-breaker,  175 

Sulphide  of  Antimony  in  Quartz  Veins,  61 

Suspended  Gold,  Mr.  Aaron's  Remarks  on,  166 

Swindling  Practised  on  the  Goldfields  in  Victoria,  Methods  of,  99 

Swinging  Plates  for  Float  Gold,  C.  G.  Yale  on,  51 

Test   for  Float  Gold  by  Mr.  Almarin  B.  Paul,  of  San  Francisco,  41 


200  Index. 

Tests  by  Mr.  G.  McDougal  of  Loss  by  Water-borne  Gold,   41 

Tests  by  Mr.  Paul  on  Losses  of  Gold,   44 

Theory  of  the  Amalgamator,   181 

Toussaint  and  Langlois,  Messrs.,  Separation  of  Gold  and  Silver  from 

their  Ores  by  Chloruration,  118 
Transmutation  of  Metals,  The,   19 

Value  of  Gold,  4,  17,  36 

Vat  Chlorination,  Introduction  of  the  "  Plattner"  System  of,   35 

Vautin,  Claude  Theodore  James,  Extraction  of  Gold  by  the  "  Wet "  or 

Hydro-Metallurgical  Process,  149 
Vautin's  Experiments,  37 
Volatility  of  Gold,  3 
Volatilization,  Loss  by,  98 

Walhalla  Mine,  Victoria,  Method  Employed  at  the,  58,  59 

Weirs  for  Collecting  Float  Gold,. 4 3 

"  Welcome  Stranger,"  The,  14 

Wind  Concentration,  188 

Wire  Ropes,  Effect  of  Saline  Water  on,   191 

Yale  on  Float  Gold,  51 


THE    END 


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GOLD  EXTRACTION  CO,  L™- 

LONDON    OFFICES, 
42,   OLD  BROAD  STREET,  LONDON,  E.G. 

WORKS  &  ASSAY  OFFICES, 

33,   Wharf  Road,  City  Road,  London,  N. 


GENERAL  METALLURGISTS,  ASSAYERS,  &c. 

Ores  Treated  in  Bulk,  Samples  Tested,  &  Advice  given, 


The  Company  have  established  an  important  metallurgical  business  in 
London,  with  branches  in  various  gold-producing  countries,  and  they  are  now 
prepared  to  receive  at  their  works  all  classes  of  ore  for  advice  and  treatment. 

The  process  has  been  in  work  for  some  years  in  different  parts  of  the  world 
with  most  satisfactory  results.  It  now  bears  a  world-wide  reputation  for  its 
excellence,  and  is  far  in  advance  of  anything  else  of  the  kind. 

On  opposite  page  will  be  seen  a  plan  of  the  general  arrangement  of  the 
machinery,  showing  how  thoroughly  automatic  it  is  in  working,  from  the  time 
the  ore  is  dumped  into  the  bin  until  the  bullion  is  obtained. 

The  plant  is  inexpensive  and  simple,  and  the  motive  power  is  small.  No 
ill  effects  of  any  kind  can  arise  to  workmen  from  the  fumes  of  the  chemicals,  an 
arrangement  having  been  made  whereby  this  is  entirely  remedied. 

By  the  use  of  the  process  the  most  refractory  ores  can  be  treated,  which 
have  baffled  all  other  methods,  the  average  returns  from  bulk  represent  from 
98  to  99 J  per  cent,  of  assay  values. 

Full  particulars  as  to  costs  and  terms  may  be  obtained  from  the  Com- 
pany's Office,  or  from  their  agent,  Mr.  C.  B.  LONGBOTTOM,  47,  Market  Street, 
Melbourne,  Australia. 

H.  S.  BAKER,  Secretary. 


RICHARDSON  &  CO., 


OZR-IB 


SWANSEA. 


RICHARDSON   &   CO.   have  been  upwards   of   50   years   established 

in  Swansea,  as 

AGENTS  FOR  THE  PREPARATION,  SAMPLING,  ASSAYING,  AND  SALE  OF 

COPPER,  SILVER,  GOLD,  LEAD,  ZINC, 

Jtnfc  all  stiver  (Dres  anb  JEetals, 

FOR  WHICH  THEY  HAVE  EXTENSIVE  WHARVES  AND  WAREHOUSES  UNDER 
COVER,  1000  FT.  OF  WHARFAGE  WITHIN  THE  FLOATING  DOCK, 

—   AND   THE   — 

MOST  COMPLETE  MACHINERY  AND  APPLIANCES. 


They  are  also  prepared  to  make  advances  against  Ores  in  anticipation  of 

realization,  and  to 

GUARANTEE    ALL     PAYMENTS    WHEN     REQUIRED. 


Several    Special   Medals   obtained   for    EXCELLENCE    AND 

PRACTICAL  SUCCESS  of  ENGINES  and  MACHINERY 

represented  by  Models  exhibited  by  this  Firm. 

HARVEY~&  CO.,  LIMITED, 

186  &  187,  GRESHAM  HOUSE, 


lIXr.     33.  G. 

WORKS    AT   HAYLE,   CORNWALL. 

Mechanical,  Hydraulic  and  Mining  Engineers 

IRON  &  STEEL  STEAMBOAT  &  SHIPBUILDERS, 

Iron  &  Steel  Boiler  Manufacturers,  Founders  &  General  Smiths 


MANUFACTURERS  OF  ALL  DESCRIPTIONS  OF 


PUMPING   ENGINES, 

AND 

Machinery  for  Water  Works,  Irrigation,  Drainage,  Sewerage,  and  Mining 

Purposes,  Sluices,  Hydrants,  Improved  Sluice  Cocks,  Pen  Stocks, 

Watering  Posts,  Valves,  Cocks,  &c.,  &c. 

Husband's  Patent  and  other  Large  Pumping  Values,  Pneumatic 

Ore  Stampers,  Special  Stone-Boring  Machines,  Stone  Breakers 

and  Crushers,  Gold  Amalgamating  and  Quartz  Crushing 

Machinery. 
NEWEST  &  MOST  IMPROVED  MACHINERY  FOR  HOME  &  FOREIGN  MINES. 

Mills  and  Machinery  for  Sugar  Plantations,  Ac. 

/BOLD  MINIM  AND  DRESSING  MACHINERY) 
I  A  SPECIALITY,  / 

Makers  under  License  of  the  "Newlbery- 
Vautin "  Patent  Gold-Extracting  Plant. 

South  African  Agency —STEEL,  MURRAY  &  Co.,  Durban,  Natal. 
Australian  Agency— McILWRAITH,  McEACHARN  &  Co.,   Melbourne. 

New  Zealand  Agency— JOHN  CHAMBERS  &  SON,  Auckland. 
CATALOGUES  AND  PARTICULARS  ON  APPLICATION. 


REVOLUTION    IN   QUARTZ    CRUSHING! 

DAVE Y,  PAXMAN  &  Co., 


ENGINEERS,     COLCHESTER,     ENGLAND, 

Sole  Licensees  and  Makers  for  the  whole  of  the  World  (excepting  the  United  States 

of  America,  Mexico,  and  some  parts  of  Australia),  of 

HUNTINGTON'S  CENTRIFUGAL  ROLLER  QUARTZ  MILL, 


FOR  FINE  PULVERISING  IN  CONCENTRATION. 


. 


NOTE.— Any  Person  or  Persons  infringing  our  rights  will  at  once  be  proceeded  against. 

D.  P.  &  CO.  ARE  MAKERS  OF 

ENGINES,  BOILERS, 

Quartz  Crushers, 
Ore  Feeders,  Frue  Vanners, 

Amalgamators, 
MINING    PUMPS, 

And  all  other  Requisites  for 

,GOLD  MINING. 

FULL   PARTICULARS 

PHOTOGRAPHS, 
And  Prices  on  Application 


Portable  Engine  from  4  to  30  HP.  nom.j; 


Horizontal  High-Press.  Coupled  Engine. 


Engineers,  COLCHESTEK, 


Improved  Mining  Engine. 

land, 


NEWBERY-YADTIN 


(PATENTS) 


GOLD  EXTRACTION  COMPANY, 


LIST    OF    PLANTS    AT    WORK. 


QUEENSLAND.  UNITED    STATES. 

WEEKLY   CAPACITY,  i                                                                    WEEKLY  CAPACITY. 

Mount  Morgan  Mine     ...      1500  tons.  |    Denver,  Colorado            ...       250  tons. 

Cloncurry                         ...       250     „  BRAZIL_ 

Norton     ...           ...          ...        1UU     ,,  «.  W  i       i  i  -r»       ~*r-                   m 

Ravenswood        100     „  <    St.  John  del  Rey  Mine ...         50,, 

VICTORIA.  BRITISH   COLUMBIA. 

Sandhurst            60     „  Vancouver                                     50     „ 

Walhalla  (Long  Tunnel)            50     „  SOUTH  AFRICA. 

NEW  SOUTH  WALES.  Johannesburg     100     „ 

Cunningar           50     „  HUNGARY. 

Ironclad  Mine 50     „  |    Nagy-Banya        50     „ 

NEW   ZEALAND.  ENGLAND. 

Thames 250     „  |    London  (Wharf  Road)  ...        100     „ 

In  addition  to  the  aboue,  Licenses  have  been  granted  for 


NOVA   SCOTIA. 


Westfield,  Queen's  County        50  tons. 


CALIFORNIA. 


Grass  Valley       250  tons. 


Several  negotiations  are  now  pending  for  the  granting  of  Licenses 
to  use  the  process  in  various  parts  of  the  World. 


H.  S.  BAKER,  Secretary, 
42,  OLD  BROAD  STREET,  LONDON. 
APRIL,   1889. 


KROM'S    ROLLS, 

FOR  GOLD  AND  SILVER  ORES. 

Sole  Manufacturers,  BOWES-SCOTT  &  READ,  LONDON. 


BOWES-SCOTT 
AND  READ 

ARK  MAKERS  OF 

STAMPS, 

JIGS, 

Amalgamators, 

BOCK  DRILLS, 
Air  Compressors, 

TURBINES, 

Silver  Quartz 
Mills, 

SCREENS. 

Jill  Mining  Stores, 


—  SOLE  MANUFACTURERS   — 

-  BOWES  SCOTT  »  READ  — 
LONDON  


BOWES-SCOTT 
AND  BEAD 

ARE  .MAKERS  OF 

PROSPECTING 
STAMPS, 

Chilian  Mills, 

WATER  JACKET 
FURNACES, 

Elevators, 

WINDING 

AND 

PUMPING 
PLANTS. 


SMALL    PLANT    SHOWING    KROM'S    ROLLS,    STONE 

BREAKER,  and  SIEVES  WITH  ELEVATOR.  All   Mining 


THE  ONLY  APPARATUS  EXCEPT  STAMPS  THAT  HAS 
SUCCESSFULLY  STOOD  THE  TEST  OF  TIME. 

BOWES-SCOTT  &  READ, 

BROADWAY    CHAMBERS, 

WESTMINSTER,   LONDON. 

Telegraphic  Address,  "DONBOWES,  LONDON."       Telephone,  3199. 


FEINTED   AT   THE   BEDFORD   PRESS,    20   AND   21,    BEDFORDBURY,    LONDON,    W.C. 


CHARLES  APPLEBY  &  CO., 

89,  CANNON  STREET,  LONDON,  E.C. 


TELEGRAPHIC    ADDRESS - 

"APPLEBYS,  LONDON." 


TELEPHONE    No.   1731. 


MAKERS  OF  ALL  KINDS  OF 

GOLD  MINING  MACHINERY. 


(2  barrel  plant,  block  No.  550.) 


SPECIALITY : 

NEWBERY-VAUTIN  (PATENTS) 
RAPID    CHLORINATION    PLANT. 


PERCIVAL  FOWLER,  M.  lust C.E..F.G.S., 

MEMBER  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS, 
MEMBER  OF  THE  AMERICAN  SOCIETY  OF  MECHANICAL  ENGINEERS,  Ac., 


J.  M.  POWER,  B.A.,  Assoc.  M.lnstC.E., 

MEMBER  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS,  &c., 

REPORT  ON  and  MANAGE 


melting 


PROMPT     NFORMATION    FROM    RESIDENT 
CORRESPONDENTS    IN    ALL   PARTS    OF    THE    WORLD, 


ADDRESS : 

PERCIVAL    FOWLER   &   POWER 

[(MINING  &  CONSULTING  ENGINEERS), 

[16,  ST.  HELENS  PLACE,  LONDON,  E.G. 


Telegraphic  Address:    "INGENIEUR,  LONDON. 


MARSHALL,  SONS  &  CO.,  LTD., 

Britannia  Works,  Gainsborough. 

Address  for  Telegrams-"  MARSHALLS,  GAINSBORO,"  and  "ENGINE,  LONDON." 

London   Offices -.-MARSHALL'S   BUILDINGS,    79,   FARRTNGDON   ROAD,   E.G. 

Telephone  No.  6648. 


Over  16,&OO  Engines  Made  and  Supplied 


Underneath  Engines.         Vertical  Engines  and  Winding  and  Hauling 

High-Pressure  or  Compound.  Boilers.  Machinery. 


Fixed  Engines,  12  to  70  HP. 
Double-Cylinder  Engines,          „,. 
High-Pressure  or  Compound .       Jap 


Locomotive  Multitubular 
Boilers. 


Vertical  Engines  with         Fixed  Engines  with  Loco- 
|  Fixed  Engines,  4  to  12  HP.          Locomotive  Boilers.  motive  Boilers 

Over  250  Gold  and  Silver  Medals  Awarded. 


IBOIILSIRS    OF 


Catalogues  in  English,   French,   German,  Polivh,  or  Russian,  Free  on  Application. 


THE 


NEW  ZEALAND  GOLD  EXTRACTION  CO. 

HEWBERY-YAUTIN  PROCESS  (Limited), 

Incorporated  under  the  Company  Acts  1862  to  1886. 


Capital,  £100,000,  in  100,000  Shares  of  £1  each. 


DIRECTORS. 
FREDERICK  THORN,  Esq.,  Chairman   of  the  New  Explosives  Company, 

Limited,  Chairman. 
HENRY    BARRETT,    Esq.,    Director   of    Barrett's    Brewery   and   Bottling 

Company,  Limited. 
PATRICK  COMISKEY,    Esq.,    Auckland,    N.Z.,   and    39,    Norfolk    Square, 

Brighton. 
CLAUDE  YAUTIN,  Esq.,   17,  Mansion  Place,  Queensgate,  S.W.,  Managing 

Director  of  the  Newbery-Yautin  Company,  Limited. 
ALFRED    JAMES    NEWTON,    Esq.,     Steamship    Owner,    8,     Leadenhall 

Street,  E.G. 
WM.    JOHNSTONS    STEELE,    Esq.,    Director    National    Bank    of    New 

Zealand,  Limited. 

BANKERS. 

THE    NATIONAL    BANK    OF    NEW    ZEALAND,    LIMITED,   71,  Old 
Broad  Street,  E.G.,  and  their  Branches  in  New  Zealand. 

BROKERS. 
MESSRS.  PIM,  YAUGHAN,  &  CO.,   1,  Drapers  Gardens,  E.C. 

SOLICITORS. 

MESSRS.    SNELL,    SON,    &   GREENIP,    1    &    2,    George    Street,    Mansion 
House,  E.C. 

AUDITORS. 
MESSRS.  COOPER  BROS.   &  CO.,   14,   George  Street,   Mansion  House,  E.C. 

SECRETARY  AND  OFFICES. 
WM.    HOLLICK,  Esq.,   35,   Bucklersbury,   E.C. 


The  Company  is  prepared  to  enter  into  Contracts  for  the  Treatment  of 
Ores,  either  on  Royalty  or  otherwise,  and  to  advise  as  to  machinery  necessary 
and  most  suitable  to  each  particular  class  of  ore  ;  to  furnish  plans,  specifica- 
tions, and  price  for  same,  and  undertake  general  metallurgical  business. 
Applications  for  terms,  &c.,  may  be  made  to  the  Secretary,  at  the  Offices  of 
the  Company,  at  35,  Bucklersbury,  London,  or  to  Mr.  D.  G.  MACDONNELL, 
.Auckland,  N.Z. 


WORTHINGTON 

PUMPING  ENGINE  GOIP> 

153,  QUEEN  VICTORIA  STREET, 


LONDON,    E.C, 


WORTHINGTON 


PACKED  PLUNGER  PUMP. 


MINE  PUMP. 


MINE  PUMP. 

PRESSURE   PATTERN. 


PRESSURE  PUMP. 


WORTHINGTOM  PUMPS  FOR  ALL  SERVICES. 

FEED  PUMPS;  MINE  PUMPS;  SINKING  PUMPS; 


&c.    &c. 


CATALOGUES    AND    PARTICULARS    ON    APPLICATION; 


ROBEY  &  CO., 


—  MANUFACTURERS   OF  — 


MM  MACHINERY  Of  ALL  DESCRIPTIONS, 


—  INCLUDING  — 


With   WOOD   or  STEEL   FRAMES. 


Improved  STONE  BREAKERS,  High-Speed  ORE  CRUSHING  ROLLS, 
GRINDING  and  AMALGAMATING  PLANTS. 


—   ALSO    OF   tfHE   — 


"ROBEY"  MINING  ENGINE  &  BOILER 

With  Patent  Wrought- Iron  Tank  Foundations, 
SPECIALLY  ADAPTED  FOR  EXPORT  AND  UP-COUNTRY  TRANSPORT. 


MINE  PUMPING  MACHINERY,  PIT  HEAD  FRAMES,  &c. 

STEAM     ENGINES     OF     ALL     DESCRIPTIONS. 

MAKERS   BY  SPECIAL    LICENSE    OF   THE 

NEWBERY-VAUTIN    RAPID    CHLORINATION    PLANT. 


FOR    CATALOGUES    AND    PARTICULARS    APPLY   TO- 

ROBEY  #  CO.,  Globe  Works,  LINCOLN. 


390306 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


ilNES 


HORIZONTAL  SHAFTS, 

FOB 

Falls  up  to  50  feet, 


AND 


GIRARD  TURBINES 


VARIABLE  WATER  SUPPLIES. 


WITH 

HORIZONTAL  SHAFTS 

(Running  at  comparatively  slow  speeds), 
FOR  FALLS  FROM  60  ft.  to  600  ft. 

AND 

HRIABLEJATEB  SUPPLIES, 

Turbine  Governors, 
Supply  Pipes,  Gearing-, 
and   all  Accessories. 


Catalogues  and  Prices  on  Receipt  of  Particulars. 

LONDON  AGENTS:  CHAS.   APPLEBY  &  CO.,  89,  Cannon   Street,  E.G. 


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Electrical  Chlorination. 

The  first  practical  demonstration  of  the  ex- 
traction of  gold  by  means  of  chlorine,  is  due  to 
the  late  Professor  Plattner,  upon  whose  dis- 
covery all  subsequent  improvements  are  based. 
The  most  noteworthy  modifications  and  im- 
provements are  those  of  Calvert,  Jackson  and 
Ott,  Hears,  Deeken,  Patra,  Rceaner,  Hauck, 
Newberry  and  others  of  less  note.  The  intro- 
duction of  electricity  in  the  extraction  of  gold 
is  of  more  recent  date,  and  the  leading  names 
of  those  who  first  adopted  this  method  are 
Pichenor,  Ancel  and  Marie,  and  Cassel.  The 
latter  patent  was  approved  by  capable  author- 
ities, but  although  five  years  have  now  passed, 
Cassel's  process  has  not  forged  its  way  to  the 
front. 

Mr.  Th.  Ranft,  M.E.,  of  Sydney,  says  the 
Australian  Mining  Standard,  now  introduces 
an  electric-chlorination  process,  in  which  he 
claims  to  have  overcome  the  vital  defects  be- 
fore experienced  in  electrical  chloriuation,  viz., 
the  getting  rid  of  the  sequent  hydrogen  and 
sodium  as  they  are  formed  by  the  electric  cur- 
rent when  passing  through  the  electrolyte.  In 
all  processes  where  the  hydrogen  cannot  be 
kept  separate  from  the  chlorine  gas,  the  two 
will  combine  and  form  hydrochloric  acid,  which 
combination  does  not  solve  gold  and  is  in  every 
way  most  injurious  to  the  process.  The  in- 
ventor does  not  claim  or  patent  any  new  law, 
but  an  apparatus  by  means  of  which  the  laws 
observed  are  complied  with.  The  apparatus 
consists  of  two  cylinders,  one  within  the  other. 
The  inner  cylinder,  made  of  a  porous  material, 
serves  four  functions,  viz.,  1st,  as  a  filter,  2d, 
as  the  negative  pole  or  cathode;  3d,  it  acts  as 
a  burrette  to  allow  the  precipitated  gold  to  es- 
cape along  with  the  caustic  soda,  and  lastly  it 
allows  the  formed  hydrogen  gas  to  escape  at 
the  top.  The  outer  cylinder,  which  is  air 
tight  (except  at  the  places  where  it  is  required 
periodically  to  discharge)  serves  three  pur* 
poses;  firstly,  it  forms  the  positive  pole  or  anode 
of  the  battery;  next,  it  acts  as  a  chlorine  gas 
generator  and  store,  and  lastly,  as  the  chlorina- 
ting vessel. 

The  process  performed  in  the  apparatus  is  as 
follows:  The  ore  to  be  treated  (free  of  sulphur, 
arsenic,  lead,  zinc  or  bismuth)  is  mixed  in  cer- 
tain proportions  with  common  salt.  It  is  then 
fed  into  the  outer  chamber,  where  the  anode  is, 
and  the  electric  currents  enter.  Water  is  then 
added,  which  dissolves  the  salt  in  the  ore,  and 
this  combined  with  the  saline  liquor,  forms  the 
electrolyte.  An  electric  current  from  a  dyna- 
mo it  then  led  into  it  by  the  anode,  and  pass- 
ing through  the  solution  into  the  inner  cham- 
ber or  cathode,  is  discharged  back  to  the  dy- 
namo. The  chemical  actions  produced  by  the 
passage  of  the  electricity  is  to  decompose  the 
electrolyte  into  its  elements.  Hydrogen  and 
oxygen  are  the  products  of  water,  chlorine  and 
sodium  those  of  salt.  Hydrogen,  being  a  posi- 
tive substance,  deposits  on  the  negative  pole; 
oxygen,  on  the  other  hand,  being  negative,  de- 
posits  on  the  positive  pole.  Chlorine  and  so- 
dium deposit  respectively  on  the  positive  and 
negative  poles.  In  order  to  prevent  the  accu- 
mulation  of  oxygen  and  hydrogen,  contrivances 
are  provided,  which  continually  wash  the  sur- 
faces of  the  anodes  to  prevent  polarization, 
which  would  stop  the  whole  process.  With 
regard  to  chlorine,  it  has  been  established  by 
Beguerel  that  chlorine  in  its  nascent  state  is 
more  active  than  afterward,  so  that  if  in  the 
ore  under  treatment  any  gold  is  present,  it 
would  now  be  almost  readily  attacked  by  the 
chlorine  and  form  itself  into  chloride  of  gold 

(Salt  Of  COldl   Which  apain   IN  «nlllhl«  in   nrafor 


The  gold  being  now  "in  solution  !s  readily 
acted  upon  by  the  electric  current.  The  mole- 
cules, as  established  by  Grotthus,  1805,  are  un- 
der  the  same  condition  as  any  other  molecules, 
which  in  their  transit  to  the  negative  zone  be- 
come  split  up  into  their  elements,  the  chlorine 
parting  and  returning  to  the  positive  zone, 
while  the  gold  is  deposited  on  the  negative  pole 
in  a  fine  metallic  condition  in  the  inner  cham- 
ber. From  this  it  is  washed  and  drawn  off  in 
the  contracted  part  of  the  inner  chamber,  in 
conjunction  with  the  caustic  soda,  and  passed 
through  a  filter.  The  powder  is  then  calcined, 
and  the  gold  remasses. 

The  gold  having  been  extracted  from  the 
ore,  the  latter  is  drawn  off  at  the  bottom  of  the 
outer  eel),  and  an  equal  amount  entering  simul- 
taneously  at  the  top  from  a  hopper,  in  which  it 
has  been  mixed  with  the  salt,  makes  the  action 
continuous.  In  a  working  plant,  every  ton  of 
ore  will  be  virtually  from  20  to  24  hours  under 
the  chlorinating  and  electrical  influence,  and 
travel  about  20  feet,  which  will  give  sufficient 
time  for  effective  treatment. 

As  to  the  cost,  it  is  estimated  to  be  about 
one-ninth  of  the  present  cost  of  chlorination,  or 
that  three  shillings  five  pence  per  ton  should 
cover  the  cost  of  supervision  and  sinking  fund 
for  capital.  The  inventor  RBtimates  the  outlay 
for  a  complete  plant  to  be  £250,  exclusive  of  an 
engine  to  drive  the  dynamo. 


THE 


old 


IT  SID 


REGISTERED  OFFICE  OF  THE  COMPANY: 


COLLINS     STREET     WEST. 


* 

'ERGUSSON  AND  MITCHELL,  COLLINS  STREET  WEST.        ijx! 


JoVIV 


THE 


IT  IE  ID. 


REGISTERED  OFFICE  OF  THE  COMPANY: 


49     COLLINS     STREET    WEST. 


MELBOURNE : 
FERGUSSON  AND  MITCHELL,  COLLINS  STREET  WEST. 


J.  COSMO  NEWBERY. 
J.  E.  GARD. 
EDWARD  WOODS. 
J.  L.  MORLEY. 
C.  W.  CHAPMAN. 


Semfarj, 

F.  H.  C.  COOK. 


CLAUDE  VAUTIN. 

Ifogtsiereb  Office. 

49  COLLINS  STREET  WEST. 

Morhs, 

MELBOURNE. 


(LIMITED.) 


THE  Directors  of  the  above  Company  desire  to 
bring  under  the  notice  of  the  mining  community 
a  New  Gold  Extraction  Process.  This  process 
is  an  improvement  on  the  well-known  Plattner's 
chlorination  process,  the  principle  of  which  is, 
converting  the  gold  in  the  material  under  treatment 
into  a  soluble  chloride,  and  in  such  form  removing 
it  from  the  ore  as  a  solution  in  water,  and  precipi- 
tating the  gold  from  the  solution  thus  obtained. 

The  principle  of  the  Plattner  process  has  received 
the  warmest  support  from  metallurgists  during  the 
past  thirty  years  ;  but  the  practical  difficulties  and 
trouble  of  applying  it,  the  slowness  of  operation, 
and  the  difficulty  of  removing  the  solution  of  gold 
from  the  ore,  together  with  the  cost  of  treatment, 
has  prevented  the  general  adoption  of  the  "chlorine  " 
or  Plattner  process  for  the  extraction  of  gold, 

Being  fully  aware  of  the  value  of  chlorine  as  a 
means  of  extracting  gold,  if  it  could  be  applied  in 
a  rapid,  cheap,  and  effective  manner,  Messrs. 
Newbery  and  Vautin  were  led  to  investigate  the 
subject,  and  they  have  devised  the  Improved 
Chlorination  Process,  by  which  they  claim  that,  by 


4  THE   NEWBERY-VAUTIN    GOLD 

the  adoption  of  the  discovery  of  Plattner,  and  the 
practical  application  of  the  improvements  suggested 
by  De  Lacy,  Hears,  and  others,  with  ideas  of  their 
own,  to  have  produced  a  perfect  gold  extraction 
process. 

In  order  that  the  following  description  of  the 
improved  process  may  be  fully  understood,  it  is 
necessary  to  briefly  describe,  in  somewhat  elemen- 
tary terms,  the  principle  of  "  chlorination,"  and  how 
it  is  applied  in  the  old  and  improved  process. 

"If  contact  takes  place  between  gold  and  chlorine, 
the  two  elements  combine,  and  form  a  definite 
compound,  chloride  of 'gold,  which  is  very  soluble 
in  water ;  and  in  this  form  the  gold  can  be  removed 
from  the  material  under  treatment  by  washing,  or 
leaching  it  with  water,  and  as  before  stated,  the 
gold  can  be  obtained  from  such  solution  by  precipi- 
tation." 

Now,  in  order  to  apply  the  above  principle  in  the 
Plattner  or  old  chlorination  process,  the  following 
modus  opercmdi  is  followed  :--The  material  for 
treatment,  after  having  been  rendered  practically 
free  from  sulphur,  arsenic,  antimony,  &c.,  by  roast- 
ing, is  first  damped,  an  operation  requiring  great 
care,  as  the  ore  must  not  be  too  wet  or  too  dry,  if 
good  results  are  to  be  obtained.  It  is  then  sifted 
into  a  large  vat,  and  chlorine  gas  from  a  generator  is 
forced  below  a  false  bottom,  and  allowed  to  rise  up 
through  and  permeate  the  ore  in  the  vat ;  this 
requires  many  hours  to  effect.  A  lid  is  then  placed 
on  the  top  of  the  vat  and  luted  down,  and  the 
whole  allowed  to  remain  from  fourteen  to  forty- 
eight  hours,  as  circumstances  may  direct.  When 
the  workman  believes  that  the  chlorine  has  com- 
bined with  the  gold,  the  lid  is  removed  and  water 
introduced  on  to  the  surface  of  the  ore,  to  dissolve 
the  chloride  of  gold  formed,  and  the  solution  allowed 


OO  /  I   7 


EXTRACTION    COMPANY    (LIMITED.)  5 

to  drain  off  through  a  filter-bed  on  the  false  bottom 
of  vat,  and  run  into  a  vessel,  where  the  precipitation 
of  the  gold  is  effected. 

This  washing  or  filtering  operation  requires  from 
twelve  to  twenty-four  hours.  In  the  event  of  the 
ore  containing  slimes,  or  being  too  fine,  it  cannot  be 
filtered  at  all,  in  which  case  chlorination  by  old 
method  has  to  be  abandoned  as  means  of  treatment. 

The  solution  containing  the  gold  is  then  treated 
with  a  reagent,  generally  sulphate  of  iron,  and  the 
chloride  of  gold  is  decomposed  and  the  gold  pre- 
cipitated in  a  finely  divided  metallic  form,  and 
slowly  settles  to  bottom  of  vessel ;  this  generally 
takes  from  ten  to  twenty  hours.  The  precipitated 
gold  is  then  collected,  dried,  and  melted. 

The  above  brief  description  is  sufficient  to  enable 
a  comparison  to  be  drawn  between  the  old  and  new 
process ;  but  if  further  information  of  Plattner's 
process  is  required,  reference  may  be  made  to 
standard  metallurgical  works. 

From  the  above  remarks  on  the  old  method  of 
chlorination  it  can  be  easily  understood  why  the 
objections,  slowness  of  operation,  and  consequent 
high  cost  are  continually  urged  against  its  applica- 
tion ;  great  skill  is  also  necessary  to  obtain  anything 
like  practical  results.  Slimes  cannot  be  operated 
on,  and  only  material  containing  gold  in  the  finest 
state  of  division  can  be  treated,  for  should  the  gold 
grain  be  coarse  it  is  in  a  short  time  protected  from 
the  action  of  the  chlorine  by  being  surrounded  by 
chloride  of  gold  ;  or  if  the  gold  is  of  low  standard, 
alloyed  with  silver,  it  is  protected  by  a  film  of 
chloride  of  silver,  and  under  such  conditions  con- 
tinual washing  and  repeated  treatment  would  have 
to  be  resorted  to  :  the  time  and  expense  of  such 
operations  thus  prevents  the  application  of  chlorine 
under  the  old  method  to  such  ores. 


6  THE   NEWBERY-VAUTIN    GOLD 

In  the  new  process  the  improvements  are  of  such 
a  character  that  not  only  are  the  mechanical 
difficulties  of  the  old  method  overcome,  but  the 
chemical  reactions  are  greatly  accelerated,  the  cost 
reduced  from  about  £1  10s.  to  12s.  per  ton,  and  the 
loss  of  gold  made  practically  nothing ;  in  fact,  a 
slow,  uncertain,  costly,  and  cumbersome  process, 
has  been  converted  into  a  rapid,  economic,  and 
effective  means  of  extracting  gold  from  auriferous 
pyrites,  refractory  ore,  tailings,  &c.,  from  which, 
when  necessary,  antimony,  sulphur,  arsenic,  &c., 
have  been  removed  by  proper  calcination. 

The  new  process  will  be  readily  understood  by 
the  following  description  and  reference  to  the  plan 
herewith  : — 

The  material  for  treatment  is  deposited  in  the 
hopper  "  A  "  over  the  chlorinator  "  B,"  which  is  a 
rotating  vessel  constructed  of  such  material  and 
in  such  a  manner  that  chlorine  has  little  or  no 
effect  on  it,  and  strong  enough  to  withstand  an 
internal  pressure  of  60  Ibs.  per  square  inch. 

The  chlorinator  "  B  "  is  charged  with  from  20  to 
30  cwt.  of  ore  from  the  hopper  "  A  "  by  allowing  it 
to  fall  into  it  through  a  manhole  ;  a  given  quantity 
of  water,  chlorine,  or  chlorine-producing  chemicals 
is  then  added,  the  manhole  cover  is  securely 
placed  in  position,  and  the  vessel  is  then  perfectly 
gas-tight.  A  pipe  leading  from  the  air  pump  "  0  " 
is  connected  with  a  valve  on  the  chlorinator,  which  is 
opened,  and  an  air  pressure  produced  as  required 
or  found  necessary,  depending  on.  the  coarseness  of 
the  gold  (the  effect  of  this  air  pressure  will  be 
explained  further  on;)  the  valve  is  then  closed,  and 
connection  with  the  air  pump  broken.  The  vessel, 
with  its  contents,  under  pressure,  is  caused  to 
revolve  for  one  hour,  when  it  is  stopped,  and  a 


EXTRACTION   COMPANY   (LIMITED.)  7 

pipe  connected  with  the  valve,  which  leads  into  a 
closed  vessel  or  vessels  "  D,"  in  which  there  is  lime 
or  soda  water ;  the  vessels  "  D  "  are  connected  with 
the  vacuum  pump  of  special  construction,  so  that 
when  the  valve  on  the  chlorinator  "  3C$is  opened, 
any  chlorine  that  may  exist  in  the  form  of  gas  is 
drawn  into  the  lime  or  soda  water  in  "  D  "  and 
absorbed ;  by  this  means  the  workmon  are  pre- 
vented from  inhaling  any  chlorine  gas,  which  would 
be  the  case  if  the  surplus  chlorine  is  not  withdrawn 
before  the  chlorinator  is  opened.  After  a  few 
minutes  the  cover  to  the  manhole  of  the  chlorinator 
is  removed,  and  the  vessel  again  put  in  motion, 
when  the  contents  are  discharged  into  the  vessel 
"  E  "  called  the  solution  separator  or  filter,  which 
consists  of  a  lead-lined  iron  vat  with  a  false  bottom, 
and  connected  with  the  vacuum  pump  "  G  "  by  the 
pipe  "  F."  Immediately  the  contents  of  the  chlori- 
nator are  deposited  in  the  solution  separator,  the 
communication  between  the  vacuum  pump  and 
filter  is  opened,  and  the  solution  of  gold  chloride 
rapidly  withdrawn  from  the  ore,  and  deposited  in 
holder  "H."  Water  is  continually- added  to  the 
surface  of  the  ore  in  the  filter,  and  the  solution 
from  it  tested  from  time  to  time,  and  when  found 
free  from  gold,  the  connection  with  the  vacuum 
pump  is  broken  and  the  filter  tipped  up,  and  the 
waste  ore  or  tailings  fal]  into  the  truck  "  I,"  and 
are  run  out  on  to  the  tailings  heap.  The  removal 
of  the  gold  solution  and  washing  of  the  ore  occupies, 
with  ordinary  sands,  about  one  hour,  no  matter  how 
fine;  when  large  quantities  of  slime  are  to  be 
treated,  extra  filters  must  be  provided. 

The  solution  of  gold  in  the  holder  "  H  "  is  then 
allowed  to  flow  through  charcoal  in  vessel  "  J," 
during  which  passage  the  chloride  of  gold  is 
decomposed,  and  the  gold  deposited  on  and  in  the 


8  THE    NEWBERY-VAUTIN    GOLD 

charcoal,  which  when  fully  charged  is  burnt,  and 
the  ashes  fused  with  borax  in  a  crucible,  and  the 
gold  obtained. 

In  places  where  water  is  scarce  the  liquid  from 
"  J "  can  be  used  over  and  over  again,  with 
economy,  as  it  becomes  charged  with  hydrochloric 
acid,  which  assists  in  liberating  chlorine  in  the 
chlorinator.  It  can  be  pumped  up  to  cistern 
"  K  "  for  further  use. 

The  lime  or  soda  water  in  the  vessels  "  D  "  can 
also  be  used  to  produce  chlorine  for  fresh  charges  of 
ore  after  it  has  combined  with  the  chlorine  drawn 
into  it,  just  before  opening  the  chlorinator  as  before 
described  above. 

Having  thus  briefly  noted  the  operation  in  the 
new  process,  we  will  point  out  some  of  the  advan- 
tages of  it, 

1st.  It  will  be  observed  that  the  material  for 
treatment  falls  by  gravity  into  the  chlorinator.  and 
is  not  damped  or  sifted  by  hand  as  in  old  method, 
for  it  does  not  matter  how  wet  it  is  ;  thus  a  great 
saving  of  time  and  labour  is  effected  at  the  very 
beginning  of  the  operation. 

2nd.  That  the  vessels  in  which  the  chlorination 
takes  place  do  not  occupy  much  space,  say  4  feet 
by  5  feet,  instead  of  siy  10  feet  by  10  feet,  as 
required  by  the  old  vat  process. 

3rd.  That  the  ore  under  treatment  is  kept  in 
motion  during  the  time  it  is  exposed  to  the  action 
of  the  chlorine  under  pressure.  The  great  advan- 
tages of  combined  motion  and  pressure  are,  that 
the  combination  of  the  chlorine  with  the  gold  under 
this  high  pressure  is  far  more  rapid  than  when 
under  the  normal  atmospheric  pressure  ;  and  no 
matter  how  large  or  coarse  the  gold  grain  may  be, 


O07I7 


EXTRACTION    COMPANY    (LIMITED.)  9 

it  is  rapidly  dissolved  ;  there  is  no  obstruction  to 
the  action  of  the  chlorine  on  the  gold  grain  by 
being  surrounded  with  a  solution  of  gold  chloride,  or 
coated  with  silver  chloride,  as  pointed  out  as  a 
source  of  failure  in  the  old  process,  for  a  fresh 
surface  of  each  grain  of  gold  is  being  continually 
exposed  to  action  of  the  chlorine,  in  consequence 
of  the  mechanical  cleaning  of  the  grain  by  the  ore 
being  in  constant  motion.  In  cases  where  the  silver 
alloyed  with  the  gold  is  worth  recovering,  or  any 
that  may  be  present  as  chloride,  it  can  be  obtained 
by  adding  salt  to  the  charge,  when,  as  is  well 
known,  it  will  go  into  solution.  This  is  a  point  of 
great  importance,  and  makes  the  process  of  value, 
and  applicable  when  the  gold  exists  alloyed  with 
high  percentage  of  silver,  as  in  New  Zealand  and 
some  Australian  mines. 

A  great  point  of  value,  and  to  which  special 
attention  is  directed,  in  the  improved  process,  is  the 
introduction  of  compressed  air,  for  by  such  means 
any  chlorine  that  would  otherwise  exist  over  the  sur- 
face of  the  ore,  in  the  form  of  gas,  is  forced  into  the 
water  with  which  the  ore  is  mixed  in  the  chlorinator. 
By  this  means  there  is  not  only  a  great  saving  of 
chlorine,  but  the  chemical  action  of  it  is  greatly 
accelerated,  and  the  gold  in  the  ore  converted  into 
a  chloride  in  one  hour  or  so,  instead  of  fourteen  to 
forty-eight,  as  in  the  old  process. 

Another  point  is,  that  in  consequence  of  the 
short  time  the  material  under  treatment  is  exposed 
to  the  action  of  the  chlorine,  many  of  the  difficulties 
experienced  in  the  old  process  are  not  encountered. 

4th.  The  time  saved  in  separating  the  solution  of 
gold  from  the  material  is  one  of  the  principal 
features  of  the  mechanical  improvements  of  the 
new  process,  for  heretofore  the  difficulty  of  leaching, 


10  THE   NEWBERY-VAUTIN    GOLD 

or  washing  the  ore,  and  thereby  removing  the  solu- 
tion of  gold  chloride,  has  been  one  of  the  great 
drawbacks  to  chlorination. 

The  rapid  filtration  is  brought  about  by  means  of 
a  vacuum  produced  under  the  filtering  medium 
in  solution  separator,  by  a  specially  constructed 
pump,  the  action  of  which  prevents  the  material, 
however  fine,  from  settling  down  on  or  into  the 
filter-bed  in  a  compact  mass,  but,  on  the  contrary, 
keeps  the  same  lively  and  open, 

5th.  The  advantage  of  decomposing  the  gold 
solution  by  passing  it  through  charcoal  or  other 
insoluble  reagents  are  numerous,  and  will  be  fully 
appreciated  by  those  who  have  experienced  the 
never  ending  and  uncertain  method  of  precipita- 
tion by  sulphate  of  iron ;  and,  moreover,  such  a 
means  of  recovering  the  gold  is  practically  auto- 
matic, and  risk  of  loss  by  theft  may  be  reduced  to 
a  minimum. 

6th.  The  cost  of  the  plant,  apart  from  motive 
power,  buildings,  and  any  calcining  furnaces  that 
may  be  required,  is  about  £  per  set  of  two 
chlorinators  or  barrels,  with  pressure  and  suction 
pumps,  &c. 

When  small  quantities,  say  fifty  tons  or  less  per 
week,  of  ore  are  to  be  treated,  the  process  can  be 
worked  in  one  barrel  or  chlorinator,  but  great 
economy  will  be  experienced  in  using  them  in  sets 
of  series  of  two  or  more,  as  the  pumping  power 
for  exhaust  and  pressure  with  the  smallest  effective 
pump  for  one  chlorinator  or  barrel,  is  the  same  as 
required  for  four  or  more. 

The  plant  is  so  constructed  that  additional  sets 
can  be  added  when  required. 

The  capacity  of  each  barrel  or  chlorinator  is  from 
fifty  to  sixty  tons  per  week. 


EXTRACTION   COMPANY   (LIMITED.) 


11 


7th.  The  plant  can  be  made  to  treat  small  or 
large  quantities  of  ore,  and  can  be  set  up  on  remote 
mines,  as  to  the  cost  is  quite  within  the  means  of 
working  miners  raising  ten  to  twenty  tons  per 
week  of  auriferous  ores,  pyrites,  &c.,  and  no 
great  skill  is  required  to  work  the  new  process,  as 
all  the  details  have  been  so  arranged  that  any  per- 
son of  ordinary  ability  can  master  the  working  of 
process  in  all  its  parts  in  a  few  days. 

The  process  is  in  full  work  at  the  celebrated 
Mount  Morgan  Gold  Mine,  Queensland,  and  it  is 
worthy  of  remark  that  every  other  known  method 
of  gold  extraction,  including  the  old  chlorination, 
was  practically  tried  by  the  proprietors,  but  with- 
out success,  when  the  rapid  chlorination  was  intro- 
duced with  such  marked  success,  that  the  loss  in 
the  tailings  is  not  (1  dwt.)  one  pennyweight  per 
ton.  Its  practical  application  to  refractory  ones 
has  been  ensured  by  the  success  obtained  at  Norton, 
Queensland,  at  the  mine  of  Messrs.  Conran  and  Co. 
Norton  ores  contain  copper,  zinc,  lead,  sulphur,  and 
arsenic.  The  United  Pyrites  Company,  Sandhurst, 
where  the  old  chlorination  process  plant  exists,  as 
well  as  the  latest  amalgamation  appliances,  are 
erecting  with  all  speed  a  plant  to  work  the  new 
process. 

The  cost  of  chlorination  proper  is  from  10s.  to 
12s.  per  ton,  including  labour  and  wear  and  tear ; 
the  chemicals  required  amount  to  about  2  %  of  the 
ore  treated,  and  can  be  so  packed  that  no  trouble 
or  risk  need  be  experienced  in  transit,  and  the  acid 
necessary  may  be  obtained  dry  in  wooden  casks. 

Any  plants  ordered  may  be  made  under  the 
direct  supervision  of  the  Company's  Manager,  and 
tested  and  stamped  before  leaving  the  foundry. 


12   THE  NEWBERY-VAUTIN  GOLD  EXTRACTION  CO.  (LTD  ) 

The  Company  will  also,  when  desired,  make 
arrangements  for  starting  the  plants,  and  instruct 
the  Working  Manager,  &c. 

The  Company  are  erecting  a  test  plant  in  Mel- 
bourne, and  will  be  prepared  to  treat  small  test 
lots  of  ores,  &c.,  so  that  mine  owners  and  others 
may  be  guided  by  actual  results.  Particulars  as  to 
cost  of  treating  trial  lots,  and  other  information, 
may  be  had  upon  application  to  the  Secretary, 
49  Collins  Street  West. 


Fergusson  and  Mitchell,  Printers,  27  Collins  Street  West,  Melbourne. 


OO7 i y 


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O07I7 


